Automation is definitely the easiest way .
Another way is to
Duplicate track,
Make 1 track Main Vox, 2nd Track Chorus
Edit/Mute parts accordingly
Add delay to the chorus track
(You can still add automation if needed…)
I do know how to use automation but I would still go with duplicating and cutting the tracks up so verse on o e set and chorus on another set. It is far more flexible and easier to follow
To have it function in real time, while singing, one might look to see if the Delay had a “mix” (wet/dry) setting, and map that to a quick controls. This will automatically record the automation on the track.