Is the level (.umap) the large file size or is it the assets that are in the level?
If it is the assets, you can use DataAsset files to split which chunk they will pak into.
By default all assets go into ChunkID 0.
You can create a DataAsset in a root folder and set to a different ChunkID and all assets in that folder and sub folders will pak to that ChunkID.
In the DataAsset file is where you set the ChunkID.
Here are my ProjectSettings.
These are the pak files in the content folder of a packaged game.
