Welcome Acblevins!
Yeah I think going along the lines of what Moo-Juice has said above is a good idea. If you really want to know the unreal development tools well enough, just dive right in and fully immerse yourself with everything. Dont worry about modelling in Blender yet, just focus on understanding what can be achieved with the engine.
The is a vast array of free assets online which you can use as placeholders for the time being, that way you can learn the editor and essentially have the ‘small playable map’ just without your bespoke made assets.