A lot, you can strip out almost everything in Windows to the level of the OS as such (as I've done since years, using the bare OS with only the needed, all other by third party FOSS). The problem in Windows is not this, but that MS calculates that the majority of users do not do it, because many things are undocumented and it is necessary to dive through countless menus and submenus to reach the corresponding configurations, often not very intuitive. This is why there are apps that take care of it. like ShutUp10, Optimizer and similar, or they directly intercept the corresponding layers on the OS like this AtlasOS.. But all this can also be done manually without problems, but with the condition that you know well what you are doing, nothing for beginners. Even so, always with a lot of caution.