If I cannot root the device from the device (no option to install from usb) I’ll have to flash twrp-3.7.0_9-0-X00P.img from my computer (ubuntu 23.10) using fastboot (bootloader)

I plan to follow this instructions: https://xdaforums.com/t/recovery-unofficial-x00pd-v3-3-1-teamwin-recovery-project-24-06-2019.3942717/ unless you mean the instructions are outdated and I shouldn’t do this. However I have questions:

the link shows this command:

fastboot flash recovery $RECOVERYNAME

I don’t understand it: Do I have to change $RECOVERYNAME with twrp.img?

Neither do I understand what follows: Boot to OLD TWRP > INSTALL > Select Image > Navigate to twrp.img > Select it & Swipe to Flash, in the device? from my computer with fastboot? As of now there is no TWRP installed in the device.

help appreciated.