i tried with doing it myself with my textured 4motion lip for my vr6 bora
if you don't want to spend a **** tonne on doing it

buy some high fill primer and do quite a few coats light at first then working your way up getting thicker and thicker
then once all texture is "filled" you can sand back with about 600 grit sand paper to make sure you don't go back down to the texture but enough for the paint to stick.
go to super cheap auto or any other paint shop and get some colour coded paint in either cans or if you have a gun do it in a gun

hang it up somewhere clean of dirt and dust and hit it with a dirt and grease remover and then again light coat at first then move into thicker and thicker coats until you get that 'wet' look
let it dry
then hit it with a good quality clear coat a few times

and then do a very light wet sand and try to polish


tbh i don't know how it would look on a big bumper as you have more to show and my lip is only small but i cbf having to pay a lot when the lip is going to get scraped and dirty so i didn't see the point of doing it "professionally"