Cable crunches to side. On knees at overhead cables....one knee pointed at weights.....other knee 90• Off. Crunch thru ribs then use obliques. That will bust out the intercostals which helps serratus separate in view.

Standing stiff armed front raises. Standing military press. The very top part of military press really pushes em out(serratus). Anything that moves arms back over head and rotates a flex to serratus. IMO a very overlooked muscle group. Adding in these movements will thicken the look of your lats hugely!

Dumbell pullovers and straight ARM pulldowns on a cable bro. I think if u Target you serratus, it will create more width to your back.

some guys do dip shrugs for these, some guys do rope pulls... but personally I don't target them specifically because mine have always been a bit more defined than other muscles around them. I think if I was going to guess it would be from doing a lot of pullovers with heavy weight. When I do skullcrushers for my tris also sometimes I use the serratus to stabilize the weight a bit higher above my head (like a pullover) and then do the skullcrushers while the serratus are tight.