I can't say it's "good" because I'm not a subject expert, but this Wikipedia page[0] is one rabbit hole to start with. A big "A-ha!" moment for me was understanding that objects small than an atom and objects bigger than an atom go in two different buckets -- and also objects traveling at or near the speed of light and those moving at more human speeds are also in different buckets. So there are 4 kinds of physics in total in the modern system:

Classical mechanics, which deals with objects larger than an atom or molecule which are moving far slower than the speed of light.

Relativistic mechanics deals with objects larger than an atom or molecule which are moving at a speed approaching the speed of light.

Quantum mechanics deals with objects smaller than an atom or molecule which are moving at speeds far slower than the speed of light.

Quantum field theory deals with objects smaller than an atom or molecule and moving at speeds approaching the speed of light.

Another good thing to lookup is the Standard Model, which contains 42 subatomic particles and is very different from what I was taught in school as a kid.

[0]https://en.wikipedia.org/wiki/Introduction_to_quantum_mechan...