I'm planning to migrate my database from on-premises to AWS RDS for Oracle. However, I'm not sure if Amazon RDS supports tools such as Automatic Fragment Advisor or the Automatic Segment Space Management feature of Oracle to control fragmentation issues. I have tried searching on AWS documentation and Google but I haven't found any official information confirming this.
"Automatic Fragment Advisor" - no such thing exists in Oracle. If you mean "Automatic Segment Advisor", that exists in all recent Oracle database versions, in AWS RDS for Oracle too.
Automatic Segment Space Management - this has been the default for user tablespaces for so many years, it is not even mentioned. Yes, tablespaces are created with ASSM by default, in AWS RDS for Oracle too.