How to enlarge the size of each sub-panel with common scale bar

[andresrcs]

@Ellenz

But if I do not add this line in the script, there will be many unnecessary areas around which decreases the size of the main area. Thus my data cannot explain the central point. Would there be some solutions?

You could manually define (fine tune) more suitable limits for the plot e.g.

coord_quickmap(xlim=c(42, 68), ylim = c(20, 35)) +