The Pixel 3a and 3a XL are capable mid-range phones, standing out from the competition by using the same high-quality cameras as in Google's flagships. With the devices being on the market for about two months now, the modding community has already had plenty of time to work on them. And indeed, TeamWin has ported its TWRP software to the two phones, unlocking their full custom ROM and root potential.
TWRP, or TeamWin Recovery Project, replaces your phone's recovery software and gives you a couple of useful features like custom ROM installation, rooting, and advanced backup functionality. The official files for the Pixel 3a and 3a XL are now available, but come with one small caveat: You can't put the custom recovery on stock Android unless you're running a kernel that supports LZMA compression. This means you'll still need to use other tools to root your phone and flash another ROM or kernel on it before you can deploy TWRP.
You can find the downloads in the source link below. If you're already running an appropriate kernel, you can alternatively install the recovery right from TeamWin's app, available on the Play Store through the widget below.