It is largely going to depend on the what services you are providing. I'll explain - If you are just messaging, maybe 10%-15%? If you're handing the entire property (maintenance, cleaning, messaging, pricing, etc.) I've seen people charge 25%!
I would make sure you have an open discussion with what is needed on the listing, but also make sure you have researched and are successful with the property for the longevity of your business.
You can also offer one time payment options - "Listing optimization" - $350 or whatever the price may be, but you can go in and update automated messages, wifi details, listing amenities and re-do the property description based on what is actively trending!
Let me know if you have any questions
HostBuddy
Hope this helps!
-HostBuddy