Dungeon Crawl Stone Soup offers plenty of ways to do it:

• Scroll of immolation definitely produces the coolest effect: it makes every enemy on screen bleed fire (dealing additional damage from any attack) and explode when they die. You can use it directly on the ogre and wound it with darts… but wouldn’t be more fun (and sadistic) to summon a weak creature and make it into a walking bomb?~
• Scroll of poison is less exciting but isn’t as dangerous as the previous solution. It creates clouds of poison on every empty tile - and all early game monsters will never venture into the clouds so you can just pelt the ogre with any ranged attacks I have by now. Not that exciting but it works!
• Darts of curare are extremely OP and it may take two-three of them to fell the ogre with no danger whatsoever. Curare is a powerful poison that deals heavy damage AND slows down its victim. You might even not lose a single dart this way as they have a chance to not be lost.
• Wands in general are extremely powerful. Paralysis might give you just enough time to stab the ogre to death. Mindburst, iceblast, acid all deal horrendous damage at this point. The question only is whether you’ll have them by that point.

any interesting ways in dnd5e to do this besides spamming ranged attacks with a flying race?