Traditional dynamics on the organ are usually a matter of registration, touch and judicious use of the swell pedal (if the particular manual has one attached).
I used Bome MIDI Translator to allow me to control all 3 swell pedals with just the one on my EL-900 and also to control the gain control of the pedal section so it too will 'swell'
Here's my initial result (don't listen to the wrong notes I was concentrating more on the GUI to give a 'performance')
Forgot to mention that I also altered the expression pedal setting for the Great and Swell making the effect more noticeable.
Two more excerpt examples.
Satie's Gymnopédies I
https://forum.modartt.com/uploads.php?f...c%2002.mp3
Czibulka-Tobani's Hearts and Flowers
https://forum.modartt.com/uploads.php?f...c%2003.mp3
This time using Bome MIDI Translator to split the EL-900's lower keyboard to add contrasting registration.
Final excerpt ...
Hamish MacCunn's Sutherland's Law (Theme from The Land of the Mountain and the Flood)
https://forum.modartt.com/uploads.php?f...c%2004.mp3