Step 1 Store Record ID's to serve as input

The Quick Merge flow action needs Record ID's to serve as input for the merge action. 

Either store Record ID's you want to merge in a collection variable in an assigment, or search for duplicate records with the Find Duplicates by ID flow action to gather Search Results to use in the merge action.

Step 2 Use the "Quick Merge" flow action

1. From the Elements section, drag a new Action to the screen from the Toolbox on the left side.
   
2. In the New Action dialog, search for Quick Merge records. 
3. At "Label", define a name for your action. If the API name is not set automatically, make sure an API name is defined as well. 
4. Option 1: If you want to merge Record ID's that are stored in a collection variable, at "Set Input Values", switch the toggle to include Record ID's.
     At the RecordIDs field, choose the collection variable.
   
5. Option 2: If you want to merge records based on the Search Result output from the Find Duplicates by ID action, switch the "Search Result" toggle to include a search result.
   At the SearchResult field, choose the duplicateResult output from the Find Duplicates by ID flow action.
   
6. At "Threshold", decide if you want to include a threshold level. Note that a threshold is mandatory when using option 2 (Search Result) in the previous step.
   The threshold level decides from what matching percentage you want to merge the duplicate records from the Search Result.
   Defining a threshold level is only possible when using the Search Result as input. 
   
7. Click Done. 

Step 3 Connect your actions to the start trigger

Make sure your actions are connected to the start trigger. 

In this example, we're first collecting an ID to search with in the Find Duplicates by ID action, after which we use the Search Result output to Quick Merge the duplicate records that are found.

Step 4 Run the flow

Run the flow by clicking "Run". 

Quick Merge action result

After running the flow, the action returns a parameter that can be used further in the flow. For example, create a link to the master record after the merge.