If they’re NOT controlling the light via homeassistant, then what you have to do is set an automation that triggers when the light is switched on and then sets the brightness/temperature based on the time of day.
It’s fairly simple, but depending on various things it may be a noticeable delay between it coming on at the wrong setting and then changing to what you want it to be.
If you DO use homeassistant as the intermediary, then you set the automation that triggers from the Alexa command to turn the light on at whatever brightness/temperature you want, and then a different automation intercepts the wireless switch and turns the light on at the correct settings depending on the time of day.
Not quite so simple, but should prevent the issue of the delay.
So maybe try the first one seeing as that’s how you’re already configured, and then if it’s not working as desired you can reconfigure to do the second way.