Blender Model Assets to Unreal Engine

So I’m working on Assets for a game but I need to know if the assets need to have actual real world dimensions for it to look right in the Unreal Engine the assets are made in blender.

You 'll have to scale them once they’re in the engine but you could set up your blender units before hand and solve that.

Here’s how the units should be set up: It’s in the scene tab of the properties window
Set unit Length to Metric and set Unit Scale to 0.01
This will translate 1 meter in Blender to be 100 millimeters UE4

A human reference scale cube in Blender will look like .3 units wide/long and 1.8 units tall (30cm and 1.8m)
If you save over the startup file, you’ll never have to redefine the unit scale again (file dropdown menu or hotkey: ctrl+u).