Is this sketch?

Well brother we can't know for sure just from what you told us,he might really need help nothing sketch about it, tiktok is region locked so he might want or think you are from a better country. Take a look on what videos he wants you to promote on his behalf and what website or etc he promotes, he might be doing something illegal aswell for example promoting crypto coins with phising websites or similar shit, but unless we don't see what he wants you to post no one can know lol

not worth it, don’t do it

This is really shady. Just block them. Unless you want to play along and see what the scam is and not do what he wants.