When I was a kid, I perceived certain cartoons to be more "cartoony" and others to be more "realistic," so basically a scale from Looney Tunes/Hanna-Barbera on the cartoony end to Transformers/Thundercats on the realistic end. [Side note: my 9-year-old self actually got annoyed at Thundercats for showing a character's head ringed by tweeting birds after he'd been clonked, because this cartoony motif didn't fit with the SERIOUS DRAMA of the cat people from outer space.]
The original He-Man and She-Ra were, as you might expect, more on the "realistic" end of my scale, holding to a design more in line with superhero comics.
I should point out this doesn't mean the animation in the "realistic" shows was good. It was often actually quite terrible, worse on most metrics than Looney Tunes. This is more about character design than anything else.
So Steven Universe definitely fits closer to the "cartoony" end of the scale, while the new She-Ra is more "realistic," though it borrows a lot of design motifs, like exaggerated expressions, from anime and anime-influenced cartoons like Avatar: The Last Airbender.
The styles are different enough between SU and S-R that it's actually a little bit of a challenge to put characters from the two shows together and have them not look out of place. To some extent the colored pencil helps with that, since it blunts a lot of the finer detail* and gives Catra a more "cartoony" feel than her in-show character design. But the anime influence in the new She-Ra makes it a little easier than, say, mashing up Steven Universe with classic He-Man, because the anime exaggerations fit better with the round-eyeball style of Steven Universe.
* This is more a product of the tools I have at hand and the paper I'm drawing on than the actual limitations of colored pencil, FYI.
The new She-Ra is really good and queer and you should watch it. The End.