I am planning to Migrate From IPS-4520 to Cisco FirePower 8350. Do we have any tools to migrate Or is there any right documentation to do that. Please do let me know.
There is a tool at https://fwm.cisco.com. I'm not sure but it may be restricted to partner access. Your partner or Cisco SE can certainly run it for you.
I would also recommend that you read the following presentation for a good overview: