Prevention of hair loss symptoms..

I'm not quite at that level yet, but

When I go to social gatherings, I personally see many people struggling with severe hair loss.

There are also some friends who have almost no bangs and cover them with wigs.

The reality is that a significant number of acquaintances around me become seriously worried just at the mention of hair.

I have also lost quite a bit of hair compared to the past (late 40s).

My concern is that I want to manage my hair so that it stops thinning from now on.

1) Is there a specific way to reduce hair loss in relation to this?

2) Is it possible to prevent this with medication?

If I take the medicine while my hair is falling out, will my hair grow back?