You can’t just resize a widget to my knowledge, you need to remove it and add a new version of it in the size you want by hitting the plus button, picking the widget, and swiping to the size and type you want.
As for not wanting to rearrange the widgets, I have no idea what you mean by “When you reset the home screen”, but wide widgets can be dragged around the same way apps can
Oh well that’s too bad... widgets position should be pinned.
Also previously the control screen widgets were immune or separate from icons to screen reset. Now apple added the control screen to reset! Poor design imho.
Apple have listed "not able to resize widgets" as a bug which imples it'll come in a later iOS release. I think they'll find that tricky due to stacks.
I've never done a home screen reset whereas you seem to be doing them very regularly. How come?
If by "keep widgets" you simply mean not having them deleted rather than having them stay where they are, then you could try dragging them to the Today screen, as that might not get reset when you do the homescreen reset thingy.