One piece you can literally finish it within half day 😈

By short I'm guessing you mean short and complete. Can only recommend what I love, so some picks are:

A place further than the universe - slice of life about some girls visiting Antarctica

Ping Pong the Animation - a lot of people get put off by the art style, but it's such an incredible show, great characters and really fulfilling

Violet Evergarden - absolutely beautiful

Kill la Kill - absolutely bonkers

So I actually run/ran a popular anime website for many years, so I have a few short series that are great:

• Paranoia Agent
• Ergo Proxy
• Land of the Lustrous
• Burn the Witch
• Cyberpunk: Edgerunners
• Freedom
• Karas

Slightly longer but not a ton of seasons:

• One Punch Man
• Chainsaw Man
• Mob Psycho 100
• Tiger & Bunny

The Promised Neverland is a good suspense one if that's your thing.

If you want to see an anime that’s really really really really weird, I suggest prison school. It’s a bit hard to find the English dub online but I’m sure you’ll find it eventually.

Kotaro lives alone is a really cute, wholesome and short anime I watched recently. It’s a pretty light watch, I’ve personally finished it entirely while working from home while coding side by side lol.