Hi Hi! And yeah ofc I can tell ya, so i use procreate idk if this is available on any other art softwares but basically

 I make a “overlay layer” which is usually either bright pink or blue(possibly other colors it depends on the OC’S color), In the layers menu their is a little “N” click on that then scroll to the bottom and click “luminosity” then lower the opacity of the layer till it looks how you want! This doesn’t really work well on OC’S with dark colors only tho btw, it’s best with neons or just bright stuff in general :,0