Connecting topology after boolean

Hi, another beginner question.
Is there a way to re-topology just a part of the model. It doesn’t really matter about topology flow, but the right connection of vertices so there are no Ngons. I have this torus where I used boolean function union. In maya I would then use the ;polyRemesh which takes just the new part and change its topology to connect it to the old one in a good way.
In blender you can remesh the whole model, or as I used the sculpting with dynotopo and smoothed the corner it changed the topology so it is actually connected in the right way. Is there a way to connect the intersection properly automatically after boolean, or to remesh just the added part?

Without addons, there isn’t something nice to achive that (to my knowledge). You could play around with the combination of triangulate and decimate modifiers. Decimate allows to use vertex groups, which might help in this situation.

Ok, and is there a possibility to triangulate/decimate just a part of the model, just the selected polygons? And about the addons, you know any?

For decimate the region to operate on can be chosen via a vertex group.

About addons, there are quite a few retopo addons around, but I am not familiar with these.