Hi Emy,
As @tomchai mentioned, you do have to take off the screen anyway to replace the battery so you're most of the way there. To do both, here's the plan.
# Follow the screen replacement guide all the way through.[br]
[guide|116036|iPhone XR Screen Replacement - iFixit Repair Guide|new_window=true]
# Pull up the battery replacement guide and jump ahead to step 20, the lower speaker replacement step.[br]
[guide|116553|iPhone XR Battery Replacement - iFixit Repair Guide|stepid=225265|new_window=true]
The only difference between the screen replacement guide and the first 19 steps of the battery guide is that the screen guide has the additional instructions for removing the earpiece/front sensor assembly that you'll need to move to the replacement screen in order to keep your Face ID function.
Following those instructions should get you right where you want to be. If you run into problems, be sure to ask for help; after all, that's the whole point of this site!
Best of luck with your repair.