In an interview, I want to hear the person without working against constant background noise. Heavy processing can also remove breath, word endings and texture from the voice.
DeepFilterNet is an open-source speech enhancement tool that can process recordings locally. Its project documentation explains file-based processing.
Listen to a short sample
Choose a passage with both speech and pauses. Keep the original and save a processed copy. Compare them at similar loudness so an increase in volume does not pass for an improvement.
Listen for clearer words, then for damaged endings, sibilance or metallic artefacts. If the voice becomes thin or broken, I would reduce the processing or return to the original.
Judge it in the film
The right amount of noise reduction may change once music and ambience are present. I would review the voice in that context rather than pursue complete silence between words.
Severe distortion or inaudible speech may need another recording. Software cannot replace sensible microphone placement.
Give the listener a clear task
The person operating the software needs time for local setup. Directors and clients can help by identifying unclear words and unnatural passages, without having to prescribe processing parameters.