I have bought everything from amazon from books to clothes to household needs, art supplies and musical instruments, as well as fitness equipment with great success. Its taken me a while to realize that not all online shopping sites are created equal though. I've had the WISH app on my phone and deleted it. Anytime I see clothing with a model of Asian descent I know I cant order those clothes.
Typical sizes of clothes are small, medium and large but there is a Japanese company that has sizes that are rather insulting. Fatyo offers sizes in Twitch, Skinny, Fat and Jumbo and the company says they’re not trying to be insulting.