After he’s been outside and given the chance to eliminate, you can put him 8n the crate, even if he didn’t go. Since he shouldn’t have enough space in the crate to soil in one end and sleep or lay at the other end, he will have to hold it. If you think he needs to go while he is in there, take him out without speaking to him, or playing, or petting or even looking at him. Make it boring, wait until he does his business, and back in the crate. Even if he doesn’t go. You do this so he doesn’t think that fussing will get him out of the crate.
It’s quite an art, but you will master it, lol !
Teach him a pee/poo command, it will help. Just say the words exactly when he is doing it, and he will start understanding after a while.