Only create new tables, don't make breaking changes to existing tables. If needed dual write both versions. Looks a lot like a live migration (zero downtime) due breaking change to a SQL DB, except you have to keep the logic longer because you're at the customer's mercy of when the switchover happens.

Also it's important to have a table that is used to coordinate latest version. If you make a breaking change have the client that is behind to ask the user to upgrade. You can also tie this into how long you keep the dual write/read around with a min version supported across all clients.