We are planning to migrate from Tridion 2013 to Tridion Site 9. Is there any script that we can run to migrate the CM and Broker to Site 9?
Upgrade to Sites 9 is supported from SDL Tridion 2013 SP1 HR1 (Hotfix Rollup 1), as stated in the SDL docs: https://docs.sdl.com/LiveContent/content/en-US/SDL%20Tridion%20Sites-v1/GUID-00D51AA4-1E17-4466-9183-F5F4932E553C
Make sure you've SP1 HR1 on top of you your existing version of Tridion 2013.
Upgrading to SDL Sites 9 from Tridion 2013 would require a great deal of planning for handling CD side of the upgrade, for example MicroServices and TopologyManager.
I would suggest to thoroughly study the upgrade part in the SDL docs: https://docs.sdl.com/LiveContent/content/en-US/SDL%20Tridion%20Sites-v1/GUID-E6995D0C-804C-4399-8EB1-044E64C33A12