One thing to know about data scientists are (1) there's the job posting and (2) there's the work. Often you'll be hired for one thing and end up doing entirely different work.

To improve your chops in this field, (a) learn the basics of NLP, (b) build yourself a RAG using llamaindex or langchain (or other but build it).

As for fine tuning and deep learning, without experience in that field it's tough. It's like any complex thing (fine tuning not so much but deep learning), knowledge comes with time and exposure. So go find a reason to fine tune or build and train a neural network and go friggin do it.