I don’t quite understand your question and I’ll try to give you an answer considering your statement that you use DPL as a raw developer:
- You can set DPL in a way to apply a preset, be it one that came with DPL or one that you made yourself. Check the manual for details: https://help-photolab3.dxo.com/en/home
You can change proportions with the “Perspective” tool. This means that you’ll have to change proportions before export and getting an exact aspect ratio might be super difficult. You might need DxO ViewPoint for changing proportions. Other than that, use the crop tool before export. You might need to drag sides or corners to get exact proportions. Check out these (and other) posts for details:
- DPL crop quirks 1:
1:1 crop ratio is not always 1:1 - DPL crop quirks 2:
Square root of two aspect ratio