Is it possible to somehow make a common stroke for all elements in an SVG file?

Question

SVG

Hello. There is an SVG image drawn with a lot of path, polygon and so on elements. Is it possible to somehow make all these elements have a common stroke? The type of contour that I will then highlight when hovering over?
Here is an example picture. It is necessary to circle each building with a contour, and combine all the contours into one object.
I don't understand SVG myself, so I apologize for the noob question.
Started using Inkscape but haven't figured it out yet.
Thank you!