Amazon RDS now supports increasing storage size when creating read replicas and restoring databases from snapshots
Amazon Relational Database Service (Amazon RDS) now supports increasing the allocated storage size when creating a read replica, when restoring a database from a snapshot, or when restoring a database instance to a point in time. This capability is supported on Amazon RDS for MariaDB, Amazon RDS for MySQL, Amazon RDS for PostgreSQL and Amazon RDS for Oracle databases.