anyway to get npcs to clean up garbage and cut random plants?

[rubish 1]

[Iyasenu]

The plants I think you'll have to clear yourself, but there's a policy you can put into place via the Home Board called Weed Sorting Campaign.
It won't get rid of plants already spawned in, but it will GREATLY reduce the spawn rate of wild plants.
There's also a policy called Waste Sorting Campaign, which will cause most trash to be automatically placed into Combustible/Non-combustible Waste boxes, if you have them built and placed inside trash zones (you'll need the Garbage Dump Sign, built at the signboard shop).

There's also a policy called Strict Anti-Littering Law, which should cause NO trash spawns, but it causes a penalty to that settlement's Civility rating (unsure what that does, though).

Finally, if you hire/recruit an NPC whose job is "Chores", they should go around and pick up garbage/junk items and place them into any shared container you have that accepts such items.

Make sure it's "Chores" though. There's another job called Cleaning, but that's only for cleaning up messy-looking tiles, like with blood on them or something.

[Astasia]

Worth noting policies like waste sorting, anti-littering, and the weed one, all have varying "success" rates based on skill level. When you first turn them on they aren't great, they maybe start at around 75% effectiveness if I were to guess, but I'd estimate they increase at around 1% per level so around 20 they are stopping like 95% of stuff from spawning.

For weeds though, you can save admin points and not use the policy by digging up all the grass. Random plants can't spawn on bare dirt tiles, or anything like wood/stone floor of course. I find this is kind of critical if you are doing delegated farming and pushing the fertility limit of the tile, just a few random weeds spawning somewhere can push you over the limit and significantly impact your yields.