Hello guys,
I've just finished rooting my S23+ with full access to system partition and I decided to make a "how to" explanation for noobies like me, as there is none at this moment and took me a lot of time to put all together. I'm not a developer, only a user so...
Be aware that rooting your phone will trip KNOX so you'll probably lose the warranty (beside the other stuff - see first step)!
First step: rooting S23+
Best way to explain how to root S23 (all of them) is done here by @dr.ketan :
forum.xda-developers.com
1. Just make sure, when you just installed Magisk (at "Instructions for stock non rooted ROM") that you check that Ramdisk is reported: "Yes" (as mentioned here: https://topjohnwu.github.io/Magisk/install.html#magisk-in-recovery ) and if that is true, you can continue with the instructions. If is not ("Ramdisk No" is probably not going to happen for S23, but just to be sure I'm mentioning it) then continue with the instructions from @topjohnwu
2. When you flash the rooted AP (see step 7), add also the TWRP recovery as "USERDATA" (see this post of @dr.ketan : https://forum.xda-developers.com/t/how-to-root-s23-s91-b-n-0.4548883/post-88465195
TWRP is available thanks to @afaneh92 here: https://forum.xda-developers.com/t/recovery-unofficial-twrp-for-galaxy-s23-plus.4558747/ , download it and use it as is mentioned above.
Now you have a rooted S23+ with TWRP so you can continue with second step: making your system partitions read-write (at this point they are read-only). Before that just make sure you copy /efs folder to your internal storage of the phone and from there to your computer. That contain very important info about your phone and a backup is a must.
Second step: making system partitions read-write
For that you need to use RO2RW tool made by @LeeGarChat available here: https://forum.xda-developers.com/t/...system-partitions-to-read-write-mode.4521131/
Download RO2RW-TEST-3.7.3.0s.zip from here https://sourceforge.net/projects/multi-function-patch/files/RO2RW/?upload_just_completed=true , put it in phone storage and install it with Magisk module. Make sure that it is enabled.
Install a terminal emulator (like this one: https://play.google.com/store/apps/details?id=jackpal.androidterm&hl=en_US )
Start the terminal and type: "su" then hit enter, then type "ro2rw" and hit enter again.
Now RO2RW is started and asking first option. Choose 1 (Make/Install) and hit enter.
Second question is about how much to expand the default size of system partitions. I choose option 5 (30Mb) as I want to delete stuff like google apps from those partitions and I don't want to increase them), then hit enter again, choose 1 (Continue) and hit enter again.
Next is about installing the Disable Force Encryption. I choose 1 (Skip) and hit enter. Now it will take some time doing stuff and will ask to hit any key to continue, just hit enter again.
Next is about removing something, just chose 2 (No) and hit enter.
Next is about backup: hit 1 (Yes) as you want to make a backup just in case... and hit enter.
Next is to chose about the backup type. Hit 2 (Recovery/Row) as you have TWRP to flash it if needed.
Next is to chose about the type of the output of your new image to flash. Chose 2 (Recovery/Row) as you have TWRP to flash. After this will take some time to finish the job... be patient.
Next is to chose if you want to force disable verification. Chose 1 (Force disable) and hit enter and done: you have the file to flash.
Before flashing, just connect the phone to your computer and copy the backup files from /internal storage/RO2RW_SUPER (you should find: super-backup-row-recovery.img, vbmeta.original.img and vbmeta_system.original.img).
Now go to Magisk, press the round arrow next to settings in up right corner and hit reboot to recovery. When in recovery TWRP just hit install, then install image, choose your file: super-rw-row-recovery.img (make sure you chose the right one and not a backup
) then for Select Partition to Flash Image select the last option: Super (system vendor........) then swipe to confirm flash and that's it. After flash you might be throw back to TWRP, just hit Reboot then chose System (maybe you'll have to do it twice) then you'll be back to your S23+ with full rw rights 
Now you can use Root Explorer or whatever root file explorer you want to play.
Enjoy!
I've just finished rooting my S23+ with full access to system partition and I decided to make a "how to" explanation for noobies like me, as there is none at this moment and took me a lot of time to put all together. I'm not a developer, only a user so...
Be aware that rooting your phone will trip KNOX so you'll probably lose the warranty (beside the other stuff - see first step)!
First step: rooting S23+
Best way to explain how to root S23 (all of them) is done here by @dr.ketan :

How to Root S23 (S91*B/N/0)
How to Root Samsung S23 (SM-S91*B/N/0) ⚠️ WARNING! Before you root your device you must be aware that This will void warranty. As of now you will lose Samsung Pay and Samsung Pass forever if you root once, even unrooting won't help. There...

2. When you flash the rooted AP (see step 7), add also the TWRP recovery as "USERDATA" (see this post of @dr.ketan : https://forum.xda-developers.com/t/how-to-root-s23-s91-b-n-0.4548883/post-88465195
TWRP is available thanks to @afaneh92 here: https://forum.xda-developers.com/t/recovery-unofficial-twrp-for-galaxy-s23-plus.4558747/ , download it and use it as is mentioned above.
Now you have a rooted S23+ with TWRP so you can continue with second step: making your system partitions read-write (at this point they are read-only). Before that just make sure you copy /efs folder to your internal storage of the phone and from there to your computer. That contain very important info about your phone and a backup is a must.
Second step: making system partitions read-write
For that you need to use RO2RW tool made by @LeeGarChat available here: https://forum.xda-developers.com/t/...system-partitions-to-read-write-mode.4521131/
Download RO2RW-TEST-3.7.3.0s.zip from here https://sourceforge.net/projects/multi-function-patch/files/RO2RW/?upload_just_completed=true , put it in phone storage and install it with Magisk module. Make sure that it is enabled.
Install a terminal emulator (like this one: https://play.google.com/store/apps/details?id=jackpal.androidterm&hl=en_US )
Start the terminal and type: "su" then hit enter, then type "ro2rw" and hit enter again.
Now RO2RW is started and asking first option. Choose 1 (Make/Install) and hit enter.
Second question is about how much to expand the default size of system partitions. I choose option 5 (30Mb) as I want to delete stuff like google apps from those partitions and I don't want to increase them), then hit enter again, choose 1 (Continue) and hit enter again.
Next is about installing the Disable Force Encryption. I choose 1 (Skip) and hit enter. Now it will take some time doing stuff and will ask to hit any key to continue, just hit enter again.
Next is about removing something, just chose 2 (No) and hit enter.
Next is about backup: hit 1 (Yes) as you want to make a backup just in case... and hit enter.
Next is to chose about the backup type. Hit 2 (Recovery/Row) as you have TWRP to flash it if needed.
Next is to chose about the type of the output of your new image to flash. Chose 2 (Recovery/Row) as you have TWRP to flash. After this will take some time to finish the job... be patient.
Next is to chose if you want to force disable verification. Chose 1 (Force disable) and hit enter and done: you have the file to flash.
Before flashing, just connect the phone to your computer and copy the backup files from /internal storage/RO2RW_SUPER (you should find: super-backup-row-recovery.img, vbmeta.original.img and vbmeta_system.original.img).
Now go to Magisk, press the round arrow next to settings in up right corner and hit reboot to recovery. When in recovery TWRP just hit install, then install image, choose your file: super-rw-row-recovery.img (make sure you chose the right one and not a backup
Now you can use Root Explorer or whatever root file explorer you want to play.
Enjoy!
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