Not necessarily. Get a carpenters level and place it on the road or path or whatever. Is the bubble in the middle.. If yes. then THAT part of the surface IS flat.. How long is the road or path. ? does it have any cures. Often highways like interstates are pitched at an angle vertically so the the even though PART of the surface of the curved road may be technically flat thee dimensionally it is curved and and has height and ?or depth... I-10 (substitute any interstate, including loops and spurs, or the Causeway Bridge over lake Pontchartrain, excuse, me it's two bridges now and has been two fridges for more than a decade. , which is 24 miles long, Curve with the curvature of earth's surface.. People do drive off the Causeway bridge and sometimes drown. Lake Pontchartrain may not be very deep, but people do drown in it., including a whole bus load of nuns..
Take ap lane trip, even on in small plane. The Higher your eyes are above Earth's surface, w the farther away the horizon become and if you look VERY CLOSELY the and you have clear vies of the horizon,, itreally is slightly curved.. This happens in tall buldings, or you can be standing on natural feature like Pikes Peak and look east over Denver and you might be able to see the curvature of the horizon..
How do you explain hills and Mountains.. Why when you drive toward them do you see the peaks first long before you you can see the base of the Mountains.. Because Earth's surface IS CURVED and has "bumps" topography, the the mountains.
If you are going to be mentally obtuse and argue endlessly no matter what anyone says, the i am wasting my valuable time answering your questions. Sometimes minds have rusted closed very tightly and thing can get through all those layers of metaphorical rust..Anything outside of your comfort zone gets rejected.