I found LLMs are pretty good at extracting ontologies through a) researching ontologies that exist for adjacent fields, there are a lot published after decades of work, b) doing multi pass ontological classifications using existing ontologies as baselines and refining, c) given ontologies attempting to represent knowledge in them and querying them along various paths with agents tasked with building recipes and techniques and evaluating them across synthetic benchmarks developed along side.
There’s also a lot of books on how to develop ontologies as well as online resources. They are all in the corpus and tasking a frontier pro level model with building a process and mental model document with references inline for grounding works really well as well for priming.