I built my daughter a new ITX PC for mainly school, and some e-gaming. It is simple, but she loves the look (unicorn...), and hopefully should be reliable, which is key for her. Yes her desk is a tip, but she is 17... and plans to take it to Uni next year. It can obviously be easily upgraded should she need.
InWin A1 Plus (which I now love)
Ryzen 5 3600
Noctua NH-U12S Chromax
WD Black 500gb NVME (plus 2x1gb SATA Samsung EVOs)
32gb Corsair Vengeance CL16 3200
Asus ROG Strix B550-I
MSI GTX 1660ti (which we already had)
Completely silent unless she boots up GTA 5 @ 1440p, and runs 3 screens happily.