how to create this gaming line animation effects when score points

You can use the screen capture video as a guide for the shape and editing of the speed graph. Start by dragging both of the speed graph handles to the bottom on the End property, then drag out the handles to accelerate and decelerate the ending speeds while checking the progress. You should see a fairly even acceleration and deceleration.

Then, do the same with the Start graph. Both starting values to zero, then drag out the end handle until the speed matches the end of the line. It should take you just a couple of minutes.

You need to add Tapers to your stroke so that the lines taper from and to their origin points.  Then use Trim Paths to control how they are revealed and disappear.  Quick tutorial here:

https://www.youtube.com/watch?v=fReYweptmtM