Hello Himanshu ,
Add a search box widget above the child list view for entities.
Bind the search box widget to a new variable in your page.
Add a data source to your child list view that retrieves all the entities related to the currently selected project.
In the child list view, add a filter based on the search query variable. You can use the "contains" operator to match any entities whose name or other properties contain the search query.
When the user enters a search query in the search box widget, update the search query variable and refresh the child list view.
This approach should allow you to filter the child list view based on the search query entered by the user, and display only the entities related to the currently selected project that match the search criteria.
Hope it helps