INSTRUCTIONS (leave a like so that more people see this):
So everything is going well but here is how I did it (Note be sure to have a computer with android-tools (for adb and fastboot):
1. make sure your device is
unlocked
2. Download your desired version of the rom (Vanilla or GAPPS, I picked Vanilla), the boot image (for rooting with magisk or flashing if you have another rom previously installed), and the recovery image
3. From within your normal rom, make sure adb debugging is enabled then do "adb reboot bootloader"
4. Flash the recovery image with "fastboot flash recovery recovery.img"
5. Perform a system wipe from within the recovery
6. Go to apply update then choose apply from ADB
7. adb sideload rom.zip
8. Voila
With my phone I had to repeat steps 4-7 again in slot a(or b)* and flash the boot image on both slots*
*Enter fastboot mode and enter fastboot --set-active=(a/b)
*fastboot flash boot.img
Side Note: it can be finicky entering fastboot mode so make sure you reboot to a screen that says one plus fastboot mode or something of the sorts