You are not going to find that policy in Hexnode because it does not exist in the Apple MDM protocol. Apple is incredibly strict about user privacy, so they do not allow any mobile device management platform to permanently force Location Services on or lock the toggle remotely. The operating system will always prioritize the privacy of the person holding the device, even if it is a corporate asset.
However, there is a very reliable local workaround using Screen Time that achieves the exact same result. You just have to set it up directly on the devices before you hand them out.
First, open the Settings app on the iPad and turn on Screen Time. Tap continue and select This is My iPad. Go into Content & Privacy Restrictions and toggle it on. Tap Location Services and make absolutely sure the Hexnode MDM app permission is set to Always. Once you verify that, select the Don’t Allow Changes option at the very top of that same screen.
Finally, go back to the main Screen Time menu and tap Use Screen Time Passcode. Set a pin code that only the IT department knows. Now the location toggle is completely locked down and your users cannot change the settings without your passcode.