what type of maintenance plan?
are you just looking for backups ? RDS handles most of this in the background, as it does with patching
you can't really backup a database to a file (easily) as RDS has no "visible storage"
Have a look at
see where that takes you
for index defrag etc, you can use sql agent and script a defrag/reindex/update statistics set of jobs using TSQL code
you might find this resource usefull
the backup bits of the script won't help you, but there is a well regarded set of scripts for index management