Many doctoral students feel anxiety about what topic to select, as high-level research develops your research focus which can impact your career trajectory. However, when you follow the research process outlined here, a topic or research question should organically arise around an area where there is a lack of information or prior research, which we call a "gap in the literature". So I recommend just diving in to the research and reading papers in the general ballpark of your area of interest. And really listen to your own curiosity and questions as they arise - that is your topic emerging!
**For doctoral students, it is important to begin your research journal at the beginning of information gathering. Make note of any search terms, notable results, etc. This record will help you to retrace your steps in the immediate, but also to be transparent about your process later when you write about it.