I've recently had to recreate some old flows for a client. The new flows are for a new object and the old ones had hardcoded ids.
So the easiest way I could find was to download the flow metadata using VSCode and do a search for 012 (the record type prefix) and find all hard coded record types.
Usually it occurs on .flow files like this <stringValue>0120X000000XXXXXXX</stringValue>
Then I created a custom label for each one and replaced the hard coded ids with a reference to the corresponding custom label.
So each hard coded instance became <stringValue>$Label.Agreement_RecordTypeId</stringValue>
