UE5 World Partition is still limited to the same Recommended Landscape Sizes from the documentation, and the equivalent large worlds based on those dimensions, such as 16x16 tiles of 1009x1009 tile size, or 8x8 tiles of 2017x2017 tile size.
Note that the calculations for the tiled worlds is different than World Composition and I’m still working on calculating what it is, since Epic has not documented it, so that I can add that to my TerreSculptor software. But for now the standard dimensions when tiled seem to work.
This is because the Landscape actor uses power-of-two textures under the hood to manage all of the Sections and LODs. So these same design restrictions are imposed in UE5 as well.
Read the Landscape Technical Guide page to see how Sections and Components relate to GPU textures, and follow those guidelines when creating any terrains.
The UE5 Landscape interface for creating New Landscapes is limited to a maximum of 8161x8161, the same as UE4, when manually creating a new terrain.
To create terrains larger than 8km x 8km requires that you import an XY Tile Set.
So computer system main memory and video memory are determining factors for how large of a terrain world you can create without running out of memory.
Importing the tiles and creating the cells uses main memory and GPU memory, and for World Partition the amount of memory used is higher than UE4 World Composition.
The basic rule of what you will require for a computer for main memory and video memory for importing and loading all cells for various world sizes is:
8km x 8km = 32GB memory and RTX-3050 8GB
16km x 16km = 64GB memory and RTX-3080 10GB
32km x 32km = 128GB memory and RTX-3090 24GB
64km x 64km = 512GB memory and RTX-8000 48GB
I run an R9-5950X, 128GB, RTX-3090 and the largest world tile set that I can import before running out of memory and failing with an error, is 44km x 44km or 2000 sq km.