Thank you for the response,
I'm using 1.12.2 since my final plan is to use these features on 2b2t (which is running on 1.12.2), and yes I know it will take time, but I thought I'd rather learn modding on 1.12.2 because maybe in more updated versions stuff have changed.
Also I managed to see the Events in Intellij, I scrolled through PlayerEvent and LivingEvent, and for example for AutoEat, the event that I see that fits it the most is LivingUpdateEvent, but it's probably not it.
I've taken a look at the tutorial you sent, but it pretty much explains how to make custom items, blocks, registering them, etc, I'm not an expert, far from it, but from how I see it, making custom items or blocks or any of these stuff won't help me in making "Hacked Clients" features, I could be wrong because as I said I'm not an expert, but I'm opened to anything that will help me learn modding, so will it actually help?