seems like the relevant plist keys are CarrierEntitlements (to be removed from plist) and APN type (to be OR'd with the tether enable mask) see here for example https://theapplewiki.com/wiki/Carrier_Bundle
(and BTW, you can find more in-depth articles by quickly googling that term in duckduckgo or elsewhere)
(and BTW, you can find more in-depth articles by quickly googling that term in duckduckgo or elsewhere)