Lots of new computers come with S mode enabled. Windows FUD says that turning off S mode will slow your computer down. Not true; installing and running lots of programs simultaneously will slow your PC down. Many ppl fret because you can’t get back into S mode once exited.
BUT you can enable the relevant security feature, only allow apps to be installed from the Microsoft store. This doesn’t provide a huge boost against malware, as malware doesn’t use an installer. This isn’t Application whitelisting.
I would recommend turning off S mode (you can do this from the Microsoft Store) and turning on “warn me before installing an app that’s not in the M$ store”. Then if a program tries to install, someone at the keyboard needs to allow it.
Via Group Policy thusly
Choose Where Apps can be Installed from in Windows 10 | Tutorials (tenforums.com)