Where? AFAIK this is a feature you need a third party app like Aldente for. The OS does not offer any way to control battery charging level. Yes, it tries to be smart and guess when you need full charge and sometimes decides to charge to only 80% but that doesnt work for all users except the ones with very regular routines and there is no manual control.
Sometimes it flat out refuses the charge. Then I disconnect and use the battery until 30% or so. Then charge when convenient (clarification: It'd possibly charge if I hit a certain percentage, but I always disconnected voluntarily, to give a good use to battery. I lasts a day. Why not?).
My MacBook Air M1 has 165 cycles in 3 years, at 90% of design capacity. I think this is a very solid management of the battery for a computer used every day literally.
My MacBook Pro is at ~85% after 8 years. I don't remember total cycles now.
I find running on battery, lots of things are throttled or disabled. CPU is slower for example. That's probably a good reason for why not.
FWIW, the performance and CPU features are the same on Mx based MacBooks whether they're plugged in or not.