Confused here. When I compile a Java program, I can specify the target platform. Even if I'm running Java 9, I can target Java 6. It it just the case of change

Confused here. When I compile a Java program, I can specify the target platform. Even if I'm running Java 9, I can target Java 6. It it just the case of change the runtime binary and continue using the version the code was developed for? Probably as a matter of regression tests, it is somewhat more risky than just using a security fix, but it would still be very rare.