This isn't a power up per se because the damage to the coast was not done by enma per se but unrestrained unleash of Zoro Ryo more than what was required.
Enma would help zoro train his Ryo and boat and thus taking his Haki to next level. Once he achieve so, enma purpose is fulfilled.
It's highly likely now that Zoro would drop enma in wano
We all know Luffy Haki wasn't a match for even Katakuri in WCI and he tried enhancing it with G4, overusing it to wins the fight which he normally couldn't, which also seems to have consequences like leaving him haki drained for dozen mins later on.
Same is the case here, we know(atleast be reasonable here) Zoro is still not at the level to slash Kaidou which even other Top tiers couldn't, bt Zoro has in it, the Haki which Enma can utilise in one single slash to make it the strongest Slash Zoro haki n body will alow him to, which imo is the only chance he stands to cut Kaidou in Wano. This Enma was perfect hour of the need in Wano for Zoro.
Yes it could be secondary purpose of Enma for Zoro, this sword needs Haki mastery else Zoro will end up using too much of his Haki which could be dangerous to both him and his surrounding or friends.
Bt Zoro imo already has it mastered to decent bit, he also used it on Monet n Pica, bt since this sword was new and he wasn't accustomed to it and used Haki unnecessarily more, the slash could have caught him off with surprise.
Maybe, bt it would have served it purpose.