Sort of. A lot of old clothes for regular folks are kind of sack like, so “fitting clothes to bodies” doesn’t quite mean the same as going to have clothes custom tailored.
Keep in mind that the fewer buttons on a nonstretch shirt (Linen being amongst the stiffest fabric, absolutely 0 stretch) means that the fit will be very wide otherwise you wouldn’t be able to put on the shirt.
As most people have shoulders wider than the waist/hips, the shirt would have to be considerably wider in those two areas for the shoulders to pass when putting it on.
That’s why polos and T-shirts are made of jersey/ knit fabrics, they stretch when you put them on and allow for few/no buttons.
I haven’t had occasion to look in Taiwan but have stocked up in Bangkok, Bali and HK before from street vendors with pretty good luck. If you go that route just have to know what long staple cotton looks like.