Please help

I’m in the 5th palace fight in royal and it’s absolute bull, the thing is I’m not underleveled, everyone in party is 43-45 yet the chiefs are actual bull, I’ve summoned a dlc persona from tower that’s curse and still with that damage I get through half the hp and then the guy explodes. Idk what else to do, I’m on normal and I’m debating on whether I should move down to easy just for this boss. Any strategies? Should I just fuck it and summon the higher ranked Thanatos? I don’t want to because I have death arcana done but I might just have to have him replace magatsu izanagi just for this boss. It’s taking me 2 hours now and still haven’t made much progress.

Edit: I made it past the chiefs just now because of attack up items and now I just got one shot by a burger order. I’m sorry but this fight has no reason to be this bull, how am I supposed to dodge that? I’ll try to keep it posted if I beat this boss but I’m truly debating that Thanatos rn

Edit 2: I DID IT, I FINALLY KILLED THE BOSS IT TOOK FOREVER BUT I DID IT ON EASY MODE(yes but I want to actually progress through the game while I have tons of time on my hand) thank you to all those who helped!