There's really not a lot of good Pokemon with rock head, but a Pokemon immediately come to mind.
Arcanine-Hisui:
This makes me think of a meme, but idk how to upload it here so I'll just quote part of it: "It (Arcanine-H) learns Flare Blitz, Wild Charge, Head Smash, Double-edge, and Morning Sun."
To elaborate it gets powerful STAB moves in Flare Blitz and Head Smash that take advantage of Rock Head's recoil negation, as well as coverage in Wild Charge. Double-edge isn't used a lot, but you can make it work. Morning sun also heals Arca9 for half of its max HP, so even if it takes some damage it can heal right back up. It also has Extreme Speed which is a really good priority move and lets it revenge kill. However, it's still pretty slow, has a mediocre attack stat with no good way of boosting it, and is outclassed by many other Pokemon like Blaziken, Cinderace, and Iron Boulder, who are just better Fire/Rock type physical attackers in most situations. It's Rock/Fire typing is also horrible defensively, making it weak to the common hazard Stealth Rock and take 4x damage from Ground and Water moves in addition to a common offensive type in Fighting, making it dead to Great Tusk, Ogerpon-W, Zamazenta, Primarina, and co if they get even one super effective STAB move off, which is why its only in Gen 9 UU.
There's also Marowak-Alola as well with its signature item Thick Club doubling its attack stat and has Rock Head Flare Blitz, but it doesn't have a very good physical movepool and I don't think is available in S/V and is only playable in National Dex.
Also keep in mind that Magic Guard is strictly better than Rock Head as it negates all forms of indirect damage including recoil and crash damage. Also, Reckless is an ability that boosts recoil damage so that's something to consider.
