Epic has released a new set of free assets for this month:
https://www.unrealengine.com/marketplace/en-US/product/stylized-nanite-dungeon-pack
https://www.unrealengine.com/marketplace/en-US/product/modular-asian-medieval-city
https://www.unrealengine.com/marketplace/en-US/product/undercity-wonderland-bundle
https://www.unrealengine.com/marketplace/en-US/product/skeleton-knight-modular
https://www.unrealengine.com/marketplace/en-US/product/rpg-user-interface-kit