learn.microsoft[.]com/en-us/windows-server/administration/windows-commands/compact
learn.microsoft[.]com/en-us/windows-hardware/manufacture/desktop/compact-os?view=windows-11
neowin[.]net/news/free-app-based-on-official-microsoft-tech-saves-huge-windows-space-with-no-performance-loss/
xda-developers[.]com/free-open-source-tool-compress-games-windows-compactgui/
Back in the day... Microsoft promoted and even sold [3rd party] tablets running the bottom end Intel Atom CPUs, 2GB RAM, & 32GB eMMC storage. The 1st ones came with Windows 8, and used a Windows utility [Compact] to compress the Windows system files because you only had 32GB to work with. They re-worked Compact for Win10, and it's still here in Win11. Files are compressed on the fly when saved to a folder marked for compression, and decompressed when read/used. There is a performance hit of course, but if you're using an SSD it's *probably* nothing you would notice.
Compact.exe is a command line app, but since it's apparently become popular with some gamers there are GUIs available. The Neowin article links to CompactGUI, which is a .NET 9 app. The app itself comes in 2 versions... one will prompt you to install .NET 9 if you don't already have it, which adds around 175MB and quite a few registry entries, but the app itself is less than 3MB. The 2nd version is 74MB, but .NET 9 is not installed, though you'll get quite a few small .Net related files added. The original article the Neowin piece is based on is over at XDA, where the author also links to Compactor. It's slightly smaller and there's no .Net, though you *may* find it doesn't look as professional as CompactGUI. Both let you choose which one of the 4 available compression algorithms is used. The XDA article has a few tables giving examples of the amount of disk space saved with a few games.