Here is Apple's advice for using your iPad:
Use iOS and iPadOS devices where the ambient temperature is between 0º and 35ºC (32º to 95ºF). Low- or high-temperature conditions might cause your device to change its behaviour to regulate its temperature. Using an iOS or iPadOS device in very hot conditions can permanently shorten battery life.
Store your device where the temperature is between -20º and 45ºC (-4º to 113ºF). Don’t leave your device in your car because temperatures in parked cars can exceed this range.
If your device gets too warm or too cold, certain features might become temporarily disabled. In extreme conditions, your device might become temporarily disabled.
If your iPhone or iPad gets too hot or too cold – Apple Support
As for a heated environmental enclosure that facilitates use in low temperatures, you will need to find a specialist manufacturer/supplier. Consider that an iPad is largely operated using a touch screen.
Some cases incorporate a protective membrane that allows interaction with the iPad's touch screen - but you must consider that the membrane will not prevent heat from escaping the enclosure, or in hot environmental conditions prevent the iPad from becoming too warm.
Cooling requires the ability to dissipate heat to the surroundings. Fans don't cool; they simply move hot air around.
Any built-in heating will have substantial power-demands.
