Hello Everyone, I need help.

If I had a door opening like 5" wide at the jamb and  I have a archway part that spans the opening of the doorway.

Lets say I make that width of the jamb larger, like 12 inches. I don't want to stretch my part, I want solid works to add another archway part to the assembly.

So for example the larger I make that door jamb width the archway part will be added to span that new door size.