When fucking, is lube required?

Vag or anal, do you need to use lube when fucking? Does your cock size have anything to do with it? Does being cut vs uncut have anything to do with it?

For me, whether fucking ass or being fucked, lube has always been a must, but never needed it for vag.

I frequently break condoms when fucking ass, which I think is due to my girth. Can't even get it in without lube.