The filter is at Filters > Map > Bump map...
select the layer you want to bump map (not the map), more about it https://docs.gimp.org/2.10/en/gimp-filter-bump-map.html
Although I prefer to use B&W maps, the Waterlevel slider is necessary to manipulate with maps using transparency as "black" if you use transparency to have the crease, or if the layer you want to bump has transpency
Also you might need to blur the full map a bit to control the edges between the whites and transparent transparent to get better control via the filter,
Last but not least, have your map and the layer you want to bump have the same size as the canvas, Layer > Layer to Image Size or you might not see it as the bumping will be on the top left corner if the map is small
select the layer you want to bump map (not the map), more about it https://docs.gimp.org/2.10/en/gimp-filter-bump-map.html
Although I prefer to use B&W maps, the Waterlevel slider is necessary to manipulate with maps using transparency as "black" if you use transparency to have the crease, or if the layer you want to bump has transpency
Also you might need to blur the full map a bit to control the edges between the whites and transparent transparent to get better control via the filter,
Last but not least, have your map and the layer you want to bump have the same size as the canvas, Layer > Layer to Image Size or you might not see it as the bumping will be on the top left corner if the map is small
Patrice