If you want to completely move away from the ‘Fortnite look’, the first thing you will want to do in UEFN is go into ‘World Settings’ and under ‘Time of Day’, tick ‘Disable All Time of Day Managers’. This will allow you to completely turn off FN lighting and create your own custom lighting setup. You’ll want to create a skysphere and create your own custom sky background or download a HDRI sky image to use as the base texture.
Then on top of that, you will want to start layering elements to build up your vista. Further away from the player, these can be 2d elements, such as distant buildings, mountains, layers of fog, things like that. Closer to the player you will start layering in low-poly 3d models that get increasingly more detailed the closer they will be to the player character.
You really only need high resolution models and textures for things that will be very close to the player character, and reduce the complexity of your assets the further away you get into the vista.