Hi @Dishen ,
Following are the steps I would follow:
1. Define the contacts criteria which needs to be exported and use advanced find to get the data.
2. Once this is done and you are getting fetch xml correctly download it (Or if you have xrmtoolbox and your filter conditions are simple then use this tool to get OData Web api query )
3. Create a flow and use List Records action in CDS(Current environment)
4. In the Fetch XML query parameter put the fetch xml you downloaded in step 2.
5. Since the records you might be pulling is more than 5000 , click on the ellipsis button the right and it will open pop up window . in this window select pagination to true and set your threshold value.
6. Use Create CSV table action after this , use output of List Records (Value) as input. Select Custom mapping from show advanced options and set your header and in column value grab the columns you want in CSV one at a time.
Thanks