My dad's account been blocked and he plays only single-player games he don't do online...

I'm having the same issue. My son wants to save his world, but every time he tries to do this, it redirects him to the page that says you need an Xbox live account. He only wants to play as a single player, not with other online users.

If by streaming with others you mean playing online with others, that is possible, but you'll want to make sure the game's he is wanting to play offer single player. If he's wanting Fallout 76 (the newest one) that is an online only game so he would be
playing online with others.

This is the dad. Yes, he is on a child account. In the past he wasnt, he is now and we recently got the game pass ultimate. Would that stop his account from being able to play online games?

It can depend on the games. The case for the discs should note if Gold is required on the back. If they require Gold, then they require an internet connection. Some games may have single player elements that can be played offline and he won't need to be
connected, but may have elements that will only work online, but he should still be able to play the single player portion without a connection.

I only play single player games and have been in the program for 8 years. There's no requirement that you play online or do anything you don't want to do.