If I understood the question correctly, you want to achieve two layers:
- First that contains only overlapping features
- Second that includes features with no overlaps
Let's assume there is a polygon layer
"grid" with its attribute table accordingly, see image below.
Step 1. Apply the SAGA's module
Step 2. Apply the following expression
if("ID" LIKE '%|%', 0, 1) in the Field Calculator.
Step 3. Continue with a
"Split vector layer" using the
"key"-field created at the Step 2. Application of
"Fix geometries" on this step may be necessary. And get the output, see image below.
Note: Mind that the final output(s) is(are) in