Is it possible to output LM317 in a parallel circuit where there are 2 voltage and has a different output voltage where one is 12V constant and the other is adjustable using potentiometer?
There is no problem connecting two or more voltage regulators to a common source, so you could have one LM317 set up as a fixed 24 volt (for example) regulator, and another LM317 as an adjustable regulator both connected to your 36 volt source.
You must provide appropriate heat sinks to deal with the power dissipation in each regulator, and ensure that the total current drawn from the two regulators does not exceed the capabilities of the 36 volt source.
If you want 2 separate regulated voltages, then you will need 2 regulators as the LM317 has only one output. The circuit shown in your question provides an adjustable output using a potentiometer. You can get a fixed 12 volt output by using a 12 volt zener diode fed from the input source feeding the LM317. However it will not be as well regulated as it would if derived from a LM317.