Hi Anu Sawant ,
When yo configure an Arcade expression in the pop-up of your webmap and consume that webmap in your Dashboard, it will be available in the pop-up of the map component in Dashboard, but also when using the details widget. You can't however use it in a indicator or for instance graph.
There is a beta of Dashboard that has more support for Arcade expressions, which can be configured directly inside Dashboard beta. To learn more about that please have a look at: https://community.esri.com/docs/DOC-14736-what-s-new-in-the-arcgis-dashboards-beta
Thanks for the reply. I am preparing this dashboard for client so don't want to create it in a beta version. Also I am using a join feature service and also related table from survey123 which I am assuming doesn't support in beta version.