This plugin is super awesome and can help with alot of the nitty gritty of foliage and level design/world building. it's called GraphN Library, and they have a LOT of awesome tools to help out in your world creation.
30 DAYS FREE TRIAL of GraphN Library: https://cutt.ly/q4Qp4nD
I don't do it justice in the video but check them out at
PolygonFlow.io
or if you want to see an even better video about what it has to offer check out their official primer video here
https://youtu.be/VbkeITmIEGk
I really can't recommend this enough, it's so fun to mess around with :D
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https://www.youtube.com/watch?v=pp_bL1IB7wk