DIY: slim jim, J pole (https://m0ukd.com/calculators/slim-jim-and-j-pole-calculator...) or quarter wave ground plane (https://m0ukd.com/calculators/quarter-wave-ground-plane-ante...). A slim jim made from 450 ohm ladder line and rolled up for storage, hoisted into a tree by a cord, is a favourite. A NanoVNA will help a lot while building any of these.

Commercial portable: Nagoya NA-771 (beware clones)

Commercial fixed: Diamond X30, X50 or V2000 colinear.

With any upgraded antenna on a receiver with little filtering like the Baofeng, you may deafen it into hearing no wanted signals if operating it in an RF-hot environment.

Don't transmit without a licence.

For portable you could buy a Diamond antenna but beware of fakes (https://forums.radioreference.com/threads/how-to-spot-a-fake...) See that you buy one with the right connector (RP?, male/female). I have an srj77 from diamond on my anytone that fits and works fine.

For larger handheld or fixed you could build/buy a yagi antenna that has a higher directionality/gain.

That was one of my first computer programs: compute a 'perfect' Yagi for a given frequency. Of course it will never be perfect because you will use tubes with a non-zero diameter and there will be something to carry the reflectors on and so on but it's amazing how close you can get if you cut and space precisely.

I've used baofeng as a base for a while. I put a home-made yagi on the roof of a shed and I could communicate with probably a few dozen active repeaters, some hundreds of miles away. Had to rotate the yagi via a state of the art "nylon rope" system.