quite confused: want to use vpn for instagram

so i tried a few apps from the app store, and they were free bc i cant invest in a subscription atm. anyways this is for a post from a celebrity that says it must be viewed if youre over 18 but my insta settings ARE over 18, so i know its a regional restriction problem. could someone guide me how to actually use a vpn and can it be used to change region detection from an app? im currently jn thailand btw.

tysmm!