Hos to dim up lights slowly with harmony remote When pressing Custom key

Sorry if this have been asked before but a general search couldn´t find an answer. Both my harmony remote and philips hue hub is added to my home assistant.

This is my very first automation, I want to slowly turn on my hue lights when I press a custom key on my harmony remote, how do I do that?

I don´t want to use harmony default home control buttons to control hue because I can´t integrate them into an activity and I can´t control how fast/slow they are turned on.

Anyone have a finished blueprint for this?