You might check out Spencer’s Ground Lease Valuation Model. You can find it here:
https://www.adventuresincre.com/ground-lease-valuation-model/
You can also find information about Ground Leases in our Glossary of CRE Terms:
https://www.adventuresincre.com/glossary/ground-lease/
https://www.adventuresincre.com/glossary/leasehold-interest/