Lots of good suggestions here already. I'd start by adding one quick note though. "AI" is more than just LLM's. Sure, the "current, trendy, fashionable" thing is all LLM's, but the field as a whole is still much larger. I'd encourage you to not myopically focus on LLM's to exclusion. Depending on your existing background knowledge, there's a lot to be said for going out and getting a copy of Artificial Intelligence: A Modern Approach and reading through it. Likewise for something like Hands-On Machine Learning with Scikit-Learn, Keras, and Tensorflow.

Beyond that: there are some decent sub-reddits for keeping up with AI happenings, a lot of good Youtube channels (although a lot of the ones that talk about the "current, trendy" AI stuff tend to be a bit tabloid'ish), and even a couple of Facebook groups. You can also find good signal by choosing the right people to follow on Twitter/LinkedIn/Mastodon/Bluesky/etc.

https://www.reddit.com/r/artificial/

https://reddit.com/r/machineLearning/

https://www.reddit.com/r/LLM/

https://www.reddit.com/r/agi

https://www.reddit.com/r/ollama/

https://www.youtube.com/@matthew_berman

https://www.youtube.com/@TheAiGrid

https://www.youtube.com/@WesRoth

https://www.youtube.com/@DaveShap

https://www.youtube.com/c/MachineLearningStreetTalk

https://www.youtube.com/@twimlai

https://www.youtube.com/@YannicKilcher

And you can always go straight to "the source" and follow pre-prints showing up in arXiv.

https://arxiv.org/corr

For tools to make it easier to track new releases, arXiv supports subscriptions to daily digest emails, and also has RSS feeds.

https://info.arxiv.org/help/subscribe.html

https://info.arxiv.org/help/rss.html

There are also some bots in the Fediverse that push out links to new arXiv papers.