Although I uninstalled the app after the finalization of the sale to those among Oracle, I used to be a long time user of Tik Tok and recall this being a feature years ago.
Interestingly, when this was rolled out, it did not require gps services from the devices, probably using geoIP lookup, and location tags on posts, either set by the creator when posting (i remember this more often than not being a feature for shitpost using absurd locations like gayville) or maybe through some machine learning audio or video to text algorithm interpreting if the post might be relevant to some geographical location if the poster didn’t tag it. I tried to find any mention of gps or location services in the article I linked and its other references, but didn’t find anything, corroborating that it was probably geoIP and some algorithmic detection.