Sarada's outfit is disgusting and pandering. In no world would this be ok - not in Naruto's fictional one, not in the real one.
And especially not after Kishimoto went to such great lengths to keep young girls looking like girls, and illustrating only a few adult women to display their sexuality, and even then it's only an extension of their power (Anko, Tsunade, Samui), not as bait.
Seeing her in older clothes than a normal Naruto-universe 12yo, with an older look and attitude and in super provocative poses, when the rest of her team/agemates aren't overly sexy, is completely jarring. And honestly, just gross.
These are characters that are simply too young to be sexualized. In a manga that historically hasn't ever sexualized the vast majority of its characters. Only for power (women) or laughs (men).
What if Sarada were dressed normally, and it was Boruto laying about across the cover, pants unbuttoned, shirt open and stroking his bare chest. It's equally disgusting and completely inappropriate as putting up Sarada in a centerfold pose, without even the hint of underwear and curve of her rear end hanging out.
Hell, why don't they just put Sarada in the center and let Boruto be the one in the pin-up pose, with no shirt, his knees tucked up and his butt hanging out?!?
If you can't take the same outfit/pose and put it on the main character, then that outfit/pose is a problem. That's not getting offended by every little thing. That's sexism.
And it stinks no less on a fictional character than it does on the real-life illustrator who thought it was an ok thing to over-sexualize a 12yo girl and market it to another generation of real-life readers. Because some of those readers will then be brainwashed into thinking that diminishing the strongest girl into just the overtly sexual eye-candy for the cover is an acceptable thing.
So what could have been an alternative cover? Remember, this is the girl who wants to be the next Kage. There could have a shot of her in an Uchiha shirt with her sharingan flashing (and why not, it's one of the most powerful techniques in their world, and arguably more powerful than anything Boruto can strap to his wrist), thus hinting at a future storyline where she has to develop and use it. And the other dude — Skeevy McSnakerson — he could have some device that hints at his future storyline. But nope. The two guys get a boys-will-be-boys look with paintbrushes, and Sarada gets a come-hither pose. Yuck.
Also, just for the sake of saying it, I would be less grossed out if this were a one-time thing. But we've seen enough shots promoting Sarada like this to know that, unfortunately, we're going to see more of them making her a fan-favorite-female by displaying her assets rather than her real strengths.