I want to know about the flight path of a specific airplane before booking the ticket. Is it possible?
There is really no way to get the exact flight path at the time of booking unless you buy the ticket at the airport. And even then the flight plan may change due to unexpected conditions or air traffic control suggestions.
The best you can do is to look at services like Flight Aware or Flight Radar 24 that will give you historical flight paths for a given flight and you can guesstimate at what the flight path will look like although certain things can happen that will change a flight path of a given or multiple flights so it looks nothing like the ones previously.