using the search function on vex form will give you loads of stuff. there is also this specific post
If you want build specific stuff there are 2 main channels that i used to learn.
- Kepler electronics. Although his buildquality inst the best and it is commonly accepted that some of the things arent done the best way its really good for explaning different kinds of mechanims like lifts, catas, passive locking mechs and all kinds of stuff.
https://www.youtube.com/@KeplerElectronics
The other which i wished i would have had when i started is Ryan 4253b. he shows some really good build techniques like Boxing, screw joints and how to properly square whcih can really bring your BQ game up.
An in general just looking at robot explanations on youtube. I learned ratchets and motor sharing through TP robot explanations and CU robot explanations i learned PTOs through TIP robot explanations and so many more things. Its gonna be a long journey but the best way to learn is just doing your own reasurch and seeing all the different mechs and playing around with them.
there is also the Vcad vex server were people post their robots and all kinds of different mechs that they are playing with can give you a bunch of ideas and places to leap off from.