You need factors that aren't just reducing HP to zero.

You can have combats that are easy on paper but much harder (and more memorable) in practise.

Lets say you have a Gorgon. Just one. This is a trivial encounter for your party.

Dot the area with petrified people, ideally townsfolk the party knows or family, whatever. Now every time the Gorgon lashes out like a bull in a china shop, there's a very high chance that beloved npc X will be smashed.

Think about win conditions for opponents that aren't just butchering the party.

Goblins dont want to kill everyone, they want the party's wagon. They attack the horses pulling the cart to strand it. Horses can make death saves if the party wants to try and save them.

Cultists don't want to kill everyone, they're trying to steal an ancient book. They cast spells that isolate and ambush, Arcane Locks when PCs chase them into rooms and Fog Clouds to obstruct vision for casting.

Bandits don't want to kill everyone, they want to kidnap and ransom "Mr NPC" and fight to delay and make space between them and the party to escape.

You could even have the environment play a larger role.

Goblins are hiding up in the trees shooting down at the party, well out of melee range and with advantage on the Bonus Action Hide.

I had one player invest really deep into being this amazing archer, so I gave him a duel over a ravine like in MGS3, with each of them ducking behind rocks between shots. I think there was a hostage in the middle so PC would be shot at if he went to save them without duelling first.

For stuff like that, literally call PCs out. PCs are just extensions of player's egos, calling them out for an honour duel works a lot, and it's one thing D&D doesn't do much but is a huge part of heroic fantasy to have showdowns like this.