To change the padding for the Data values use the padding setting which can be found in the Data label section in the Layout tab as shown in the image below. The images further down show an example of a line chart with different padding values applied. The image below shows where to find the padding setting.
(The setting is not shown for stacked/full stacked bars and columns as these charts use zero padding by default.)
The top line chart below uses 5 pixels padding which is the default value. By setting the padding to 0 pixels the chart will look like the second image below: as shown the data values are displayed closer to the line which might be better in cases of having many lines as it is easier to see which value belongs to each data point.