I am trying to start an exe that is located in C:/Program Files (x86)/App from UWP app. How can I do this.
I can start exe file by using Windows Desktop extension fo
You cannot start an arbitrary EXE from your UWP app process. What you can do is launch your own full trust EXE in your own package (as you already discovered). From that EXE you can then launch the arbitrary EXE (assuming the user has the privileges to access it). So it's a two step process for this scenario in the arbitrary case.
A better option is to launch the other app via a protocol (but this may not always be an option, if you don't own it, or it doesn't support protocol activation).