I have been asked in the past if the stated size of a country takes into account the curvature of the Earth and/or its topography. My usual answer was "in reality both affect it but I doubt if the official figures reflect this as historically the data was either not available or the calculation was too cumbersome".
It's very easy for kids to prove this by looking at an imaginary hill/mountain and calculating its surface area. Assuming a hill is a perfect hemisphere it is clear that the surface area is twice that of a flat circular area of the same radius. A conical hill is over 2.4 times the surface area of the flat surface. So obviously anything over perfectly flat will have a larger surface area - its just a question of how much.
I swerved the curve of the Earth question as being only really important for very large countries like Russia, although I suppose you could look at the surface area of the Earth and work out the proportion that country covers.
Since those days God invented computers and airborne/satellite imaging.
I was ploughing through Matt Parker's Stand-up Maths videos and came across this:
Well worth a watch - Switzerland is bigger than it is. I suppose places like Nepal and Tibet must also be bigger than they are.
The Bosnians say that ‘Bosnia would be bigger than Russia if you ironed it...’