In Postgres there is a GRANT syntax for all object of a certain type including all future objects https://www.postgresql.org/docs/current/sql-alterdefaultprivileges.html. For example:

GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA public TO myuser;
ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT, INSERT, UPDATE, DELETE ON TABLES TO myuser;

Schemas are not supported in Firebird at present, but it does not matter for the current task.

This syntax can be very useful if it is necessary to create separate database user in addition to the database owner, for example, for some application server access, with full read-write access but without access to alter metadata. At present we have to update grants explicitly after every database metadata upgrade.