No - not possible. When tethered to your iPhone, from the perspective of your iPad, you are simply accessing a WiFi network connection. Hardware features of your iPhone are not accessible to your iPad.
As you are evidently aware, WiFi Only models do not have any GPS capabilities. These devices are entirely reliant upon the WiFi connection with which to estimate their approximate location - using a lookup of detected neighbouring WiFi networks and the public IP Address of the WiFi network to which it is currently connected. This technique can be reasonably accurate with fixed WiFi in urban and metropolitan areas, but is far less accurate/reliable in rural or less populated areas.
It is possible to add limited GPS location capabilities using an external GPS receiver - either using a plug-in module or a Bluetooth connection. BadElf receivers are often used with iPad for Marine and Aviation applications - and have good reputation.
https://bad-elf.com/
I hope this information and insight proves to be helpful.