Sorting Individual WBS levels

The short answer is no. A sort parameter only applies to the whole Layout. But within the WBS window you can promote or demote individual WBS values within their parent value. So one WBS code at a time you can determine the sort order of an activity layout grouped by WBS.

WBS STRUCTURE 1

You re-group a WBS structure by creating a new one.

WBS STRUCTURE 2

You can sort any WBS structure if using sorting by columns/multiple columns and using a User Defined Field to enter sort values at the WBS bands/rows.

Needless to say you can create a nes WBS structure for every sorting of your choosing.  Another option might be to fill all rows, WBS bands as well as activity rows and use this single column for your sorting.

I do not believe P6 will allow you to create multiple WBS structures but it shall handle some WBS sorting if using sort by columns.

you can group by wbs then sort by something else within the grouping. If you want a finer and more flexiable grouping and sorting capabilities I would sugguest that you create activity CODES and assign the proper activity codes to the activities.