How to modify thickness of existing graphics in Inkscape?

Question

I have an existing svg image:

source: https://www.svgrepo.com/svg/165174/thought-bubble

And I'd like to modify the thickness of lines to be a bit slimmer. How could I achieve that in Inkscape?

The manuals suggest editing stroke and fill but I can't seem to find any way to have these attributes influence the image.

Answer 1

I figured out. path->inset (ctrl+)) did it!