The correct solution (as with languages on websites) is to auto-detect but then make it super easy and obvious how to change if the auto detected version is not what the user wants.
Also if any web developers out there are reading - don’t use the user’s location to determine the language/region they want, and especially don’t force it. I have no idea why so many websites do this but those responsible deserve to permanently have small amounts of sand in all their socks.