You can't set the options on multiple databases in one statement. But you can set multiple options on one database in one statement.
ALTER DATABASE <db> SET READ_ONLY, SINGLE_USER
[ WITH { ROLLBACK IMMEDIATE | NO_WAIT | ROLLBACK AFTER nn SECONDS } ]
Both READ_ONLY and SINGLE_USER settings will be blocked if other users are in the database, the termination clause specifies what to do about them.