You tin usage the Activity 'Assign Item Categories' (ID: 102807) to fulfill this requirement.
In this activity, determination are galore combinations of 'Sales Document Types' , 'Item Category Group', 'Item Usage' and 'ItemCat-HighLevItem'. You tin take the 1 operation that fits your needs and acceptable a 'Default Item Category', specified arsenic 3 'Manual Item Category'.
You tin cheque the authoritative documentation: Flexible Item Category Determination - Standard Determination | SAP Help Portal