1. you will probably run into an issue trying to pull this one off...a channel is its own widget. a widget within a widget i believe is not doable in the current state.
2. i believe you can adjust channels with the current layout of 1/3rd screen, ½ screen, full screen

Thanks for replying, @dklinger. Can you talk more about your response to my question #2? I know you’re referring to row layouts with the sizes you mention. How does row size configuration play into channel size adjustments? How would I go about doing that?

Hi,

Let me provide you my experience with channels:

1. One can’t iframe the internal pages. So even if you create a seperate page for a channel widget and then try to iframe as @dklinger says it, not doable. So, you will have to create a widget only.
2. No, height of the widget can’t be changed to your liking. However, width has to be as per the standard sizes of the widget- 1,½ or 1/3 the size. So you are offered a choice of three widths. Hope this helps. 

Thank you @Rais for reiterating - I was rushing a little. Good luck @EmilyG