Resize canvas

I am using Premiere Elements 2024.  I captured a video on my iPad Pro 12.9" in landscape mode.  I want to keep only a portion of the area of the video.  For example, the video has what I want in only a portion of the screen.  I want to eliminate everything outside that portion.  Then I want to edit the video by trimming the start and end points which is no problem.  Then I want to export/save the video to be shown on a cell phone screen in portrait mode, regardless of the phone model or screen size and have the entire portion fit.  I tried using the crop tool, but this didn't work, as I had a lot of black screen remaining around the cropped area.  I tried setting the project settings to Mobile > iPod, and kept the project settings when adding the clip.  But I still had a full landscape image.  How can I set the canvas size to be the correct size to ensure the end result will be able to be shown on a cell phone screen?  Note: the portion that I want to isolate is the right size for the cell phone screen, so I don't think I have to resize the image itself.  I just need to get rid of everything around it and have no black screen around it.