The underlying rule that populates the results of "My Work" in case worker portal is in "MyDashboardMyWorkList" section rule. It is an available rule for the users to implement the changes necessary based on their requirement. Hence, you may modify the repeating grid to include few more properties to display in My Work by performing SaveAs of the section rule to your application ruleset. Note that you can give the column only of the properties that are already present as part of the data page results, otherwise you can also modify the data page which is the source for repeating grid as per your requirement.
By default we have Name, Case ID, Category configured in the repeating grid. If you need any other extra column that has to be populated, make sure that you have that data in the data page which is actually the source of repeating grid (for which, as mentioned you will have to modify the data page to have the content loaded).
Otherwise, if you have case specific details that are to be displayed on click of each case, then you can do that by configuring the repeating grid to use Master detail" in operations tab, use Display of details and specify the flow action that would display the details.