Hello!
You can create a faction and transfer land claims to faction ownership. By default your faction can have up to 10 land claims. With faction-owned land claims it's also much easier to manage access rights (no need to do this individually for each land claim).
If you want to raise the personal limit on the number of land claims, you can adjust it in the server rates settings. You need to adjust "Additional land claims number" setting.
You can do this right from the game if you have server operator access rights (you can do this by editing Data/SettingsServer.xml file). If you're a server operator, please log in to your server, press ESC key and you will see a menu containing a button to browse the server rates—there is also a "Edit" button right next to it (if you don't see it, please ensure that you have server operator access rights).
Regards!