fastboot boot TWRP.img is not rebooting into TWRP

[a_wolfie]

This is a Pixel 3 (just to be clear). I have unlocked my bootloader successfully. I have installed the latest factory images (not OTA). I have re-allowed USB debugging. Downloaded the latest TWRP (twrp-3.3.0-0-blueline.img), and the zip (twrp-pixel3-installer-blueline-3.3.0-0.zip) placed the zip on the phone in the downloads folder. I reboot to bootloader. I open Win 10 command prompt (ADB and Fastboot is in PATH). Change directory to where TWRP img is saved. I type "fastboot boot twrp-3.3.0-0-blueline.img" I see:

Sending 'boot.img' (65536 KB) OKAY [ 0.286s]
Booting OKAY [ 3.407s]
Finished. Total time: 4.618s

My phone reboots but boots into system, not into TWRP.

I assume it is a NOOB mistake... I have looked at https://twrp.me/google/googlepixel3.html, and https://forum.xda-developers.com/pixel-3/development/twrp-3-2-3-0-pixel-3-t3861622, and https://www.xda-developers.com/google-pixel-3-unlock-bootloader-root-magisk/

Not sure what to do next as I would like to root. Any input would be appreciated.

 

[sliding_billy]

Android 10 has no TWRP support for Pixel.

 

[a_wolfie]

So how do I root the first time? Load an old factory image and then fastboot the TWRP image? Everything seems to say the same instructions, which I have tried to follow.

 

[sliding_billy]

So how do I root the first time? Load an old factory image and then fastboot the TWRP image? Everything seems to say the same instructions, which I have tried to follow.

Read the guide. Nothing to do with TWRP. https://forum.xda-developers.com/pixel-3/how-to/guide-patching-boot-img-magisk-canary-t3964359