Realistically a good starting point to read up on could be about admin privileges. Or ring 0 in software. It basically boils down to the fact that anything that is running as root ( or with admin privileges) can read and write to ANY file it wants to. Effectively having full control over the system.
In other words it could be used to do anything they want with your pc. An example of that actually happening is the anti Cheat that genshin impact is using because that was exploited in that way already.
There is no consent in “you have to agree”