Often you need to install the specific version of a Package in Unity Package Manager to match the requirements of Unity Tutorial or Unity Asset.
There are 2 ways to do it for Official Unity Packages and Git Packages in my New Unity Tutorial.
take note of the name like com.unity.xr.arfoundation
press the + and then install by name, type in the name and under it is a box you can put a version number in.
note, depending on which version of unity you use it may auto update it if you say hope to a new version of unity (eg a new release)
So, this is what I’m talking about in the tutorial. If you don’t need an auto-update, because the target Unity Tutorial or Unity Asset may not work with the newer version of Package. So, you can fix the target version manually.
the newer versions of unity (2023+) seem to auto upgrade, i dont remember it doing it before, or if it did, i never had trouble till it auto did it with 2023… but you do have to change the unity version to trigger it, and a lot of sensible people dont just install new unity versions at the drop of a hat… they do it like at best every few months.