Using a Local LLM on a home laptop

I'm not educated when it comes to LLM at all but recently I've been pondering the idea of using a local LLM to help me with worldbuilding, feedin the llm with things I need like conlanging to ease the process of constructing languages etc. How possible is it to have one on a laptop. I was hoping the llm works in an isolated way without being intercepted by some stuff it picked up from the internet that gives me a mixed outcome that fucks with the LLM. I hope what I'm asking is making sense, thanks in advance.