In the Models tab, double click on “DAM update asset” workflow.
Double click to edit the 14th workstep Processing Thumbnails. In the dialog box we can see under thumbnails tab some default resolution configurations in a multi-field, to which we can add or remove our custom resolution configuration too.
After adding the custom resolution, Click OK and save the workflow from top left and close the workflow console.
The custom rendition of the resolution that we added will now be generated for every asset that is uploaded in DAM.