The BricksUltimate add-on added the new dynamic data tag {loop_counter} and you can display the loop counter in your posts list. It will work inside the Query Loop builder.
Step 1: Add the Container element and enable the query loop builder
Step 2: Add the Post Title element inside the container element.
Step 3: There has Prefix control inside the Post Title element and set the dynamic data tag {loop_counter}.
You will get the loop counter without any code or CSS.