Is he unironically the strongest character in the OPM universe?
Not in terms of physical strength but in the sheer ability to win fights or at least to never lose. He is very similar to Saitama in that neither of their powers are based on any physical rules, instead they both have control over the narrative. No matter what opponent Saitama faces he will be strong enough to defeat them in one punch. The same way no matter what opponent King faces the events will unfold in a way so that King will come out on top. So they both have the ability to warp reality in their favor.
I think he'd have a legit heart attack You know that "King Engine" He knows what Saitama can do
Tyler Myers
Proof that luck isnt a dump stat.
Brody Wood
Nothing is stronger than plot armour and a maxed out luck + charisma stats
Hudson Lee
King would obliterate Saitama with an infinite combo and Saitama would crush the controller.
Julian Thompson
The plot would never align to allow it. If it did, King would just run away or pull an excuse to not fight out of his ass, and Saitama would just let it happen because he doesn't punch people with his full strength.
Also, Saitama knows King is full of shit and King knows Saitama isn't, so again, from a narrative standpoint, it's a fight that just wouldn't happen.
It shouldn't need to be argued that Saitama COULD easily kill King without really needing to try. It simply goes against the point of both of their characters to consider the matchup.
James Mitchell
You could say that the only possible confrontation between them are their video game battles where King wins every time. Therefore King is the strongest being.