>Build the cliffs/grounds out of lowpoly geo with a tiling scan texture. Tesselate + displace it.
>Use particles/procedurals to spawn rock scans on your ground (not sure how you do that in Maya but use the same technique as foliage)
>Use scans for the logs
>Buy a couple tree + plant models, or make them yourself in speedtree (use scans for leaf/bark)
>Use speedtree for the hanging vines
>Figure out how to do a proper water shader, do absorbtion, refraction, surface waves, water line with bubbles + debris around objects
>Get some procedural moss on your rocks, start with shaders + textures but you can supplement with tiny autistic moss meshes
>Use the same procedurals to spawn foliage on the ground, pebbles on the ground, dead leaves on the ground, dead leaves in the water. Remember to paint unique scene-wide masks or vary your breakup so your procedurals show where you want them to be and don't look dumb as shit.
And don't forget to
>Block out camera + FOV
>Block out scene
>Block out lighting
>Check PBR values (texture albedo, light color + intensity, exposure, correct SSS color + depth on foliage)
Don't trust scans to be accurate, many of them have bad calibration including Megascans.
If you don't want to use scans you can learn how to do all this by hand, it'll take a couple years.
Hope this helps.