for example there is 7 level elements, how to only bring let's say all elements for level 3(no category, template) by pi builder to spreadsheet?
You generally just need to set the Element Search Root to the specific level:
If you have multiple top level Elements each with 7 hierarchical levels, then this will only return the elements below the specific branch selected. If you need to return all level 3 hierarchy members regardless of where they are in the overall tree (multiple branches), then this approach will fail. That is where you will need to look at the use of Element Categories to provide the search dimension that could return what you need.
Retrieving data ...