The size fitted packs are usually limited so stay away from those. Nxe, pbrack, and valken have similar pack belts (one size fits all and has a double belt design). If I remember correctly, sly and empire dont dont have the double belt design and the packs might run small. A lot of people say that x gear runs small, forgetting that these companies segmentation is the youth group so the sizes are closer to youth than to adult. It would be like putting on a youth large t-shirt. Anyway, I am 193 lb, 5'11 and wear 36 pants and have no problem with nxe style packs.
to a forum convo about people who are size 40+ that are having fitment issues with the nxe pack.
also sells an extender for the waist.
But honestly If you are finding that you have problems fitting an nxe pack comfortably, then its probably better to lose the extra fat instead of extending the band. You're long term health is better for you and your family. gl