The Wahoo app lets you do this. Are you able to connect to the KK Smart Control via the Wahoo app? I am not sure that's possible because KK annoyingly decided on a proprietary data format.

I am not certain but I do think the Kinetic app allows for that but since I gave up on the smart control only a few weeks after buying it (returned the somewhat useless thing), I ditched the app.

I presume that's a "smart control" version, and not the "smart"?

Assuming its the smart control, then provided you've got a Bluetooth phone, you should be able to use any of the apps in a free ride type mode.

Personally, I've found Rouvy good for this. Pair and calibrate with your trainer, and then you can set your wattage as required using up and down arrows.
The free version will only allow 1hr sessions before you need to kick it back in again.