What you need is a compressor which is a filter in Shotcut but I never used it. I use a compressor plug-in (TDR Kotelnikov) in Audacity which is not exactly comparable.
I could try to explain it but I am not a professional and I think with so many tutorials out there, it is not really useful nor necessary. I honestly would just search for a video on how to use a compressor; that is what I have done.
Edit: I guess you liking my post means it gave you the clue what to search for? If that is the case, you could mark it as the solution. Or otherwise, you can ask further questions .