Inside the MetaHuman_BP there’s already a LOD manage ( called LOD sync ) that takes care of handling polycount, shader complexity and also manage the joints reduction.
Consider that for a project I did a while ago, I had a Metahuman running on the Quest2, so you can definitively have performance boost if you know what settings you need to tweak.
Also you can force the LOD manually if you need ( by default the LOD are set automatically based on distance ), so that you gain performances in editor.