Realistically, this just depends on your artistic needs for the game and what you’re willing to live with. Mobile doesn’t have the luxury of being as tweakable with scalability settings on the fly as a PC game would.
If you’re targeting a wide-range of devices I would say that you need to find a cutoff for what is acceptable for your game based on the lighting, overall art quality (textures, models, effects, etc), and the type of gameplay needed. If these things will directly impact the gameplay mechanics then I’d say target mid-higher end devices, whereas if it were something like a Match3 game you could target a wider range since lower quality wouldn’t directly impact gameplay.
Like with any generation of devices (phones, pc GPUs, consoles) there needs to be a point where you focus on future proofing your game or developing for the market that will be in place when it’s finished instead. Sacrificing quality features is sometimes more detrimental IMO, though.
This is a pretty good breakdown between HDR and LDR if you’ve not seen it in our documentation: Performance Guidelines for Mobile Devices in Unreal Engine | Unreal Engine 5.1 Documentation
Edit:
what type of shadow is being displayed then?
Dynamic shadows are the absence of light by masking out shadow casters. This is why dynamic lighting has darkened areas.
Modulated shadows use this mask and give you an RGB color range to adjust the masked area for shadowing. It’s not as accurate as dynamic shadowing, but you have more artistic control and it’s cheaper to use!