Is there a tag for when lips look like a doughnut, or a squashed tire, or otherwise an un-pinched encirclement of the mouth-hole? Stereotypically these show up on black characters, or Mr. Popo.
EDIT: Well, that was foolish: those were gritted teeth (I blame bad eyes and defaulted resizing), though this caught my eye as similar before looking at the post again. And I'll admit, the scant Popo-posts here aren't very good examples of what I had in mind. Instead (for another trim example), I'll try pointing at Usopp?
I fail to see any link between Mr. Popo's lips (post #1175875) & post #931128. pouty_lips seems to be an existing (but underused?) tag for larger-then-average lips. Or if you meant a round mouth without lips, that's fairly common ~ tags like :o.
The open mouth in post #931128 were probably being mistaken as lips.
As for pouty_lips, looking at the posts it is most likely for full lips like in post #950078. I wouldn't have used it for Mr. Popo's lips like it is being used in post #1175875. It's not simply that the lips of full or larger than normal, it's the fact that the lips are for the most part shaped as a single band around the mouth. It's as if someone took a wide rubber band and taped it around the person's mouth. Images like post #950078, the lips are at least recognizable two parts where in the lips the OP is referring to they're like a single "doughnut" around the mouth. Hassan Fullbrush from Kyoukaisenjou no Horizon is another character with those kinds of lips (post #995531 top row, 3rd from the right, the one with a plate of curry).
A wikipedia depiction of these types of lips, used to stereotype African Americans Link
Guess it's better to make a new tag for it then, altogether there probably are a few 100 posts fitting the tag. exaggerated_lips - huge_lips - doughnut_lips ? I have no idea.