Blue jeans plus layers. For my DD short sleeve or thin long sleeve tops and soft hoodies. It isn’t fashion forward, but she blends in.
Leggings would work too, but my kid doesn’t like them.
Mine is 17 a and has strong opinions about clothes— she knows what she likes, which is solids, dark and jewel colors, classic cuts, etc. but, she HATES shopping. She’s starting college next year, so I just got her started with Stitch Fix. She took the quiz, wrote the stylist a note about what she wanted, and got 2 pairs of jeans, two light long sleeve shirts and a cute cardigan that all tie together as her first fix. She kept it all except a pair of jeans that didn’t fit right.
The delivered to the door/ mom doesn’t choose the clothes/ not being dragged through the mall approach works well for her.