What a good question! I think there’s a lot of confusion about this, but it’s easily solved by trying out the filters… I’m also not sure what Dan suggests, with Size, Position, and Rotation. I used this a lot before, with KDEnlive, but it required a lot of tricks🛞, like Gottfried Leibniz!
I think most people are looking for a magic filter (Crop: Source Video Filter), like when we set a background image🖥️, enlarged↕️ to fill it.
Now I’m recording a lot vertically, so I “make” the rest of my videos vertical.
In effect, assuming you’re going to work with a default resolution all the time: Choose the resolution Choose the filter Crop the px to where you want it until it fills Save the setting and select it later