We know that we can display multiple column in the dynamics 365 lookup view but there is a limitation that you can only display maximum three column in the lookup view, though we can add multiple columns in the lookup view but you can see only first three columns in the lookup view. This is a limitation in Dynamics 365, Microsoft mentioned here.
Now how to display more than three column value in the lookup. You might be thinking to create a field where if we can store concatenating multiple fields value with some separator and add the field in the lookup view. So now to do this you may need to go for workflow /plugin/JS which is additional work.
Why not we go for calculated field where we can concatenate multiple fields and add the calculated field in the lookup view. I did the same with calculated fields and now I can display more than one field value in my lookup view.
I have created a calculated field (type single line text) in account entity and concatenate few fields with “/” separator which I want to display in the lookup view.
My calculated fields working fine, see below screenshot.
Now I have added the calculated field in the Account lookup view and do save and publish all customization.
Now I can see more than three column value in the lookup view.
I have also answered similar question in Dynamics CRM Community.
Hope this helps 😊.