I used this when installing fresh copies of Windows 11 and was very satisfied with it. I never thought about it increasing RAM as the author says, I was just interested in disabling CoPilot, all telemetry options, changing the start menu and task bar to act more like Windows 10 and various other options.
Winutil is definitely a tool I wouldn't recommend for a beginner, as many of the options are things you wouldn't want to mess with, but it will create restore points for you to put things back. You can hold your mouseover the options to see what it's doing and click on the question mark icon to learn exactly what it
s doing. Since it also lets you run O&O Shutup, it's getting rid of a lot of phone home garbage and tracking you want off too.
I use it and the WinAero tweak tool [1] just to keep Windows Update disabled until I can be sure the slop updates Microsoft puts out are actually working or not, since recently half the time they break something serious in the OS.