Hi,
The NXP Community support channel is intended for questions related to NXP products and their applications. Your question is about general Analog IC design education, which falls outside the scope of NXP technical support.
For learning progression advice, the r/chipdesign and r/ECE communities on Reddit are well-suited for this type of discussion and Razavi's own lecture series on YouTube is an excellent next step after completing the introductory chapters you mentioned.
Feel free to explore NXP's training resources at nxp.com/training for additional learning materials.
If you have a question related to a specific NXP product, we are happy to help.
BRs, Tomas