Similarly, I live at sea level, and researched this question extensively some years back (and try to stay updated) before a race in the Alps. The short answer would be ’not really’ in terms of physical benefits. That said, those short trips could help you adapt mentally to how it feels to move at altitude and how to pace your effort. I was able to arrive a week early as part of vacation, which allowed overcoming the biggest dip in altitude effects, but it was the opportunity to gauge my effort at altitude and the more extreme vertical that paid off the most. Big difference going from a 40 m ski hill to non-stop 1000 m climbs, and the ability to adjust mindset to that was critical.

Plus you’ll get to spend time on the route. Road test nutrition, sort out some route finding. Just general familiarity is worth the time in my experience.