Delay one side of the stereo outputs?

The Kemper does not have that specific effect in it. In a studio, a plugin would be used - or, a better approach would be to play the part twice.

But, If you want it for live gigs, here is a way to do it (by getting 'creative' with the way things are designed)

Delay Time & Delay Ratio(Only in Free Delay and Analog Delay).
The “Delay Time” is set in milliseconds. The “Delay Ratio” determines the ratio of different delay times between the left and right delay taps. The “Delay Time” always represents the longer delay tap, the other “Delay Time” is just a divider of the displayed time.

For a 30ms delay on one side:
Set Delay Mix to 100% - Wet
Set Delay Time to 40ms
Set Delay Ratio to 4:1 (This will make one side delayed 40ms, and the other side delayed 10ms (a 30ms difference )

I don't know how many run their live rigs in stereo - Of those who do, some prefer not to use a short delay like this, because, depending on the song's tempo, phase cancellation can make the guitar sound smaller than a mono guitar.

There are some other options: some use the "stereo widener" (a pitch based effect), some do use stereo delay (but, with less than 100% wet, so there is a center signal with no latency). Chromatic Pitch can also be used, with different parameters than the Stereo Widener effect.

There have been previous discussions about this effect - you may want to search to see if there is a feature request where you can add your support.

If not, you can add a new feature request, to see if you can accumulate some +1 votes

Andy Sneap has requested this effect for live broadcasts that they regulary do.
On a PA in a live venue this delay will have no positive effect. If you stand in the audience more to one side of the PA, you will experience a one side delay anyway. An aritificial delay will would not necessarily intensity this effect. But to the audience that stands very close to the delayed side, you will constantly sound 30 ms too late.