Hi, I implemented dynamic resolution in a patch to my game on Android. The effect is great, it allows to balance the resolution against the GPU performance. Of course, it won’t fix CPU related issues, but this works perfect for all GPU related slowdowns. The downside is when the change of resolution occurs - you can clearly see it on aliased edges, hence it is worth to consider implementing AA. Here you can see it easily with no AA enabled and quality settings & lowest resolution possible exaggerated for the device.
You can check how it works here: https://play.google.com/store/apps/details?id=com.konradzaba.VornsAdventure (the game is free with no ads!)
At first it starts with max resolution equal to 1280x720.
Then after a while where new area starts to be visible it goes down to 1227x691
Once water reflections are there, it goes to lowest resolution possible 534x300 to keep reasonable performance.
Next when there are still reflections rendered but less models in scene it goes up to 628x354.
And it ends with native 1280x720.
If you are interested, I can provide a code sample.