How can I find underwear for myself?

Hey guys I know it's very strange question to ask but here I am

I'm 6feet tall guy with heavy build 113kg in weight and i want a brief ( an underwear type) unable to find any because my size is 3xl and it's very hard to buy online and pls don't say just buy from a local shop I'm very shy in Nature and this feels very awkward for me

I'm tired of searching online because every underwear has bad reviews with some good ones too and after reading those review I can't buy anything because I don't wanna waste my money but it's been 2-3 days of continuous searching and the search is still going on

Pls help guyss suggest me some good underwear ( briefs if possible) 3xl size.

I'm using a xxl size brief underwear of xyxx but I it felt lil on the tighter side that I'm going for 3xl and xyxx also don't have any 3xl size underwear

Pls help!!!!!