Interface input gain usually changes the analog gain before conversion. Clipping is not a required processing step: it happens when a stage cannot handle the signal, or deliberately limits its shape. For a clean DI, set the gain so that the hardest picking still has room, instead of trying to keep the meter full.
The app's input Trim multiplies a signal that is already digital. Trim can balance the level driving the next pedal, but it cannot restore peaks already clipped at the interface. Turning down a clipped file produces a quieter clipped file.
Floating-point processing can store internal values above normalized full scale without automatically hard clipping. Distortion occurs when an operation is nonlinear, clamps values, or passes through a limited stage. Keep headroom at the output/interface. Intentional drive clipping differs from unintended overload.