To be honest, I can’t think of any tools that would fit your task. I’ve always done this kind of manual search.
First, you need to find influencers in the niche you are interested in, so you can access similar profiles, since they will probably subscribe to them or even have publications with tags.
Next, you need to study the audience of the profiles you are interested in and also search through their signatures. That is, in this way you will be able to use the snowball method to find various accounts in the niche you are interested in.
And of course, direct search via the search bar or hashtags on social medias.