1) Add values in the ranges section of the Charts area. Ideally, the range that needs to have values hidden does not intersect with any other lines. In this example, Range 1 is going to have the last few data points covered up.
2) Add a rectangle shape off to the side of the chart. Change the color to match the scene's background. If the background is not a solid color, take a screenshot of the background where the line will appear and upload it as a custom asset.
3) Place the image over the values to cover them up.
Optional step - apply the Slide Up Enter Effect and adjust the timing using the timeline:
If Slide Up Enter Effect is added, it will appear in the video like this: