Hi, just export your character from Blender to UE and verify the export settings to make sure blend shapes are properly exported. Your character must be rigged either with a full body + face or only the face if you’re exporting only the head mesh.
In UE, the setup consists in using the ARKIT shapes in combination with facial bone controls (either control rig/anim blueprint or skeletal controls/anim blueprint). All methods below require an iPhone X or newer. If you don’t have one, there are other methods that use a webcam and can provide good results.
A quick example of a custom ARKIt character setup is provided by Polywink with a sample FBX/Maya scene available for download in the webpage:
Motion Capture Avatar From iPhone - Facial animations for everyone! (polywink.com)
For more advanced setups with facial bones (eyelids, eyes, jaw + neck and head), three other sources are available:
The UE4 sample project Face AR shows how to setup a ARKIT character with eyes, neck, head and jaw bones controlled by skeletal controls/anim blueprint, and the video below is the original live stream exploring that sample project.
Face AR Sample in UE Legacy Samples - UE Marketplace (unrealengine.com)
Face AR Sample | Unreal Engine 4.27 Documentation | Epic Developer Community (epicgames.com)
Introducing the FaceAR Sample Project | Live Training | Unreal Engine Livestream (youtube.com)
The sample Windwalker Echo includes a setup for ARKIt characters with a full body control rig + anim blueprint and is available from UE 4.27 to UE 5.2:
Windwalker Echo in Characters - UE Marketplace (unrealengine.com)
You’ll find more recent tutorials on YT for UE5 with control rig, which offers more refined controls than UE4’s skeletal controls. Both methods can be used in UE4 and UE5.
A third method is shown by Trash Praxis, which consists in replacing the ARKit blend shapes by full facial bones control, making use of pose assets. Mind that it can be tricky to make the pose assets without a control rig:
