A YouTube user has uploaded a thorough tutorial on importing high poly models to UE5.
A YouTube user JSFILMZ has uploaded a great tutorial to the channel. In this tutorial, JSFILMZ explains how to import high poly models to Unreal Engine 5. To do so, JSFILMZ uses Nanite, a new system in UE5 for efficiently rendering masses of geometry. The demonstration scene is taken from the author's previous work.
There are many demonstrational videos on the channel that showcase the capabilities of Unreal Engine 5, so we highly encourage you to visit JSFILMZ to learn more about the engine.