iPhone XR gets a bit hot. Is it normal?

Yes. To reiterate from the previous comment, warm to mildly hot temperatures can occur often on media-streaming related, and social apps such as SnapChat. While I have an iPhone 8, apps such as Instagram, particularly looking at Stories, or in YouTube for a long period of time, it gets warm. While in most cases it's considered to be normal, I would keep close eye with your system settings, checking for background apps or apps requesting to push data and notifs to your phone, like email or social apps. Also look into your battery health under Settings > General > Battery > Battery health, to check for data and insights from your use or non-use of the phone.

Should there be any other issues you're wary of, contact Apple Support.

It warms up from use and is related to those apps.