Coming from the old school, you can use Fruity Peak Controller and Fruity Balance. Put Fruity Balance on the channel you want ducked (use it on a buss to route multiple channels to the sidechain). Put the Fruity Peak Controller on the channel you want to act as the trigger (bare in mind FPC defaults to muted at the bottom). The mute function is handy if you are using a ghost trigger.
Link the FB volume control to FPC Peak with mapping formula: 0.81-Input
This will link it inversely to the trigger. The 0.81 is the default position of most volume controls/faders. 0 being -inf and 100 being max. Think of it as a percentage. I don't know if this is an advertised figure or not, but I worked this out through experimentation many years ago. It has been my go-to method for most of my 14 years.
This is as versatile as it gets. You can then control the wet/dry of the Fruity Balance, as well as the Base, Vol, Tns and Dec parameters on the Peak Controller for the shape of the duck.
