Price change when a large investor sells a lot of a stock?

Just curious about what happens / how things are calculated ahead of time when a large investor sells a large amount of stock, e.g. $5 million of a single stock, or, for that matter, $20 million, in a large lot.

My understanding is that unless someone is looking for a lot that large, it's broken up, and the price changes as it's sold.

Is there any way to see what happens ahead of time, or follow large trades like this?

What strategies do they use?

TIA