There is a concept called correlation that let us see more clearly if two assets move on average in the same way even if there are moments in which they move differently, some time ago I took the time to do this experiment and with a correlation of 1 meaning that the assets are moving exactly the same way, -1 which tell us they move in the opposite way and zero which means they move independently from each other, altcoins have a correlation of 0.9, which tell us their movements are heavy correlated to the way bitcoin moves.
It is cool to learn that there was also a test done for this. I am assuming that the 0.1 loss was due to some of the coins having some issues which resulted with them going down. Aside from that I am pretty sure that unless something unexpected happens, the movements are nearly the same.
I know that it will not be simple, I know that it will take time but I also know that it is a great deal that we should all be looking for most of the time. Obviously it is not going to be 100% exactly the same move, the amount it goes up and down could be different, while bitcoin goes down 5%, ETH may go down 8% and bnb may go down 3%, or same when its going up, but the direction will be the same and seeing a confirmation done in experiment is great to know.