Tropical Island level design

So atm I want to make a pirate game such as sea of thieves, for some experience. I just want to work on a project so get started with unity again. But I’m kinda stuck with the level design. I want to make a tropical island, but whatever I do, I just can’t get the hang of it. It always looks very empty and unprofessional.
Can anyone help me with maybe a tutorial or something similar? Maybe some tips?

I’m going for a low poly look btw.

There are 2 ways of making the low poly terrain. 1. way is to make a model of the island in blender and then just import it to Unity. The second way is to make the terrain using unity terrain editing tools and then use a low poly shader. But if you don’t have any experience with writing shaders, or you don’t want to buy some, I would recommend you to go for the first way :). How to make your island not to look empty? You have to focus on details. Put there few types of rocks, some kind of grass, palms, cactuses, whatever you can find on a tropical island.