Curtain wall doors adapt to fit the panel size. In this case, a legend component, the host is determined by the host length in the options bar. Unfortunately, there is not a host height for you to select as well. So when you change this length, it will make your door square with the same height and width as the "host length". In other words, it is a limitation of the software and requires a work-around currently.
So, you either need to:
1. add symbolic lines on a subcategory that you will only turn on in a legend view, making the lines snap to non-boundary lines which you can define;
2. Create a detail component which looks like your door; or
3. Create an elevation of the door panel the same way you do with the curtain wall itself, isolating the panel instead of the frame. You will need to remove the view title from this view if you want it to be with the other doors in the legend.
I recommend option 3., at least for now, but the reality is we need the ability to adapt the height and width of a curtain panel in the legend components.
