There's a few things you can do
Use the binoclars by pressing the 3 key
Use of Zoom
You can cycle through the Zoom options while flying using the Z key on your keyboard.
The "keep ground in view" will make the plane very small. The field of view is always 30 degrees.
In "manual zoom" you can zoom in or out with the + (or =) and - key up to 15 degrees FOV angle.
In "autozoom" it will zoom itself and keep you at 15 degress or you can change it with +/-
It might be useful to know your distance by using NavGuides. To see the NavGuides press the 1 key. If you're not showing distance to aircraft and zoom level then Choose Gadgets > Edit NavGuides and check the box on 'distance to aircraft' and 'field of view' in the pilot section.
Change the visual size of the plane
Choose Aircraft > Edit (aircraft name) then choose Vehcle tab and edit the Vehicle Graphical Scale (%)
The plane will fly the same as the original - it just looks bigger