If you’re aiming to get really deep into Bitcoin’s tech side, I’d suggest starting with the Bitcoin Developer Documentation—it’s pretty comprehensive. I’ve also found BitcoinTalk forums really helpful for technical discussions. For a solid book, “Mastering Bitcoin” by Andreas Antonopoulos is a goldmine. Plus, online courses on Coursera or Udemy can be a great way to get structured learning.
Man, you are on the bitcointalk forum right now

But the Bitcoin developer documentation is a good place to start, but it's not thoroughly explaining everything in the Bitcoin protocol, just the basic early parts, since it hasn't been updated in a while since around Segwit I think. The Mastering Bitcoin book is better at filling the blanks, but failing that then you can consult the Bitcoin Wiki.