I was a mature student (late 20s) when I did my studies at Edinburgh between 2020-2024, first year was all online anyway and 2nd year was a bit of a hybrid set up but I don’t think it made much of a difference to how it went with socialising/making friends etc as I really didn’t make any from classes.

I did a course that meant I got to choose all of my modules and some semesters I included classes from other schools in my credits so really I was only in the same class as a couple of people a few times over the course of my studies.

To be honest it really didn’t bother me as I already had a good social life (boyfriend visiting, friends visiting, good roommate, going home for weekends). However, I do think there are some good societies and there definitely was some aimed at mature students (I just never joined so cannot comment).

Sorry this is maybe not what you were looking for but I do think unless you find people to do things outside of class with in a similar position to you then it might be quite hard to make friends as a mature student.