You could create animations and then have them play back on your character. You could utilize sequencer to play a movie within your project. Some reference materials below.
You could do it by setting up livelink here (Iphone 8+ required): Facial recognition in UE4 | How to setup Live Link & ARKit w/ Anime VRoid studio & Unreal Engine | - YouTube
You could then use livelink paired with sequencer here: Learn how to use MetaHumans Pt. 2 | Use sequencer, animation retargets and iOS face recognition
OR you could use the facial rig here: Using the MetaHuman Facial Rig in UE | Unreal Engine - YouTube