Hi Ben,
It’s best to optimize for the platform your developing for. The more performance that is required can stress the device if things have not been optimized. You’ll want to avoid dynamic lighting, complex shaders, highly detailed meshes, and scenes with a lot of complex geometry. These are very broad suggestions, but essentially the more complex your scene and the more that is required will be more stressful on the device. If you’ve not read through it already, I would suggest starting with this page in documentation: General Mobile Development for Unreal Engine | Unreal Engine 5.1 Documentation
Looking a the GPU (Adreno 306) that is with that device is a very low-end GPU for mobile when compared to the Mali-t760 that is with the S6.
Benchmark results:
Adreno 306: Qualcomm Adreno 306 - NotebookCheck.net Tech
Mali-T760: ARM Mali-T760 MP8 - NotebookCheck.net Tech