I’ve never seen such valve installed on a sump pump discharge line and I can’t find anything that could be used in this application. There are adjustable pressure relief valves but have different purposes and it doesn’t appear that they can be adopted for the sump pump.
You could install “Y” connector with a manual valve right above your sump pump and run a second pipe to exterior – bottom leg of the “Y” to sump pump, one top leg of the “Y” to the existing line and the second one to the exterior. You could also put two valves so you can close the existing line and open the one that would discharge to exterior, whenever the storm sewers are overflowing.
This “Y” connector and manual valves can be also installed on the exterior but you’d have to go outside to control it.
You could also put a second sump pump in the pit, with a switch (pressure / floating) positioned above the main pump and a discharge pipe extended to the house exterior. This would activate the second pump whenever the first one has a problem with keeping up with pumping water. It’s good to have a back-up…