As inasaba has said, Stoic philosophy is very helpful for simple living, but a book from a different school of thought that I really found quite a bit of value in is How to Do Nothing by Jenny Odell. It discusses a variety of ways to resist the attention economy of social media while also not becoming a hermit, by building small, local, and intentional communities, and setting aside part of your day to just mindfully doing something that brings you joy (The titular 'doing nothing') Plus, it's popular enough that there are usually a few copies at your local library. If that's not simple living, I don't know what is!