With the method discussed here you can add a list of labels to categorize generated topics. This isn't quite what you're looking for but it does create a two level hierarchy.
Reference: https://neuml.github.io/txtai/embeddings/configuration/#topi...
Reference: https://neuml.github.io/txtai/embeddings/configuration/#topi...
Expanding functionality to include something like this is possible though. The community detection algorithms kind of do this in a way. Each iteration builds smaller and smaller communities.