There are some really, really nice baggies that are quite stretchy and sit well. I still wear bike shorts under for protection from the saddle.
I have some Fox Ranger shorts which are comfortable and hard wearing but I’d suggest there are plenty of great options and go try some on if you can (mine are shorter than I’d prefer).
Wear your bibs (or comfy bike shorts) as opposed to the supplied MTB liner if you are spending decent saddle time as the MTB liners aren’t the same quality of Chamois by any stretch of the imagination