hello! I compiled a list of different apparel stores that sell trendy, 'young' clothes! These stores all have different specific styles/aesthetics...

Retail & Online:
Forever 21
H&M
Target
Pacsun (eh pretty overpriced imo)
Express (also expensive oops)
Urban Outfitters (expensive too)
American Eagle (only like the jeans tbh)
Brandy Melville (expensive & stores not everywhere)
American Apparel
Topshop
Free People (also $$$$)
ZARA
Mango
Sport specific personal faves: Nike and Adidas

Online only (at least from where I live I can only access online):
be careful when buying on online stores LOOKOUT FOR SCAMS
Zaful
Boohoo
Missguided
FashioNova
Romwe
Lulu's
NastyGal
Asos
Pretty Little Thing (Boohoo is its parent company)
Shein
Revolve
Reformation
InTheStyle

THRIFT STORES ARE ALSO GREAT SPOTS TO CATCH SOME BARGAINS

i'm gonna continue to update this fyi