Line Sparkline is one of the mini charts that are placed in a single cell, representing the trend of data that you have selected. Please see how to insert line sparklines, and follow the steps below to format line sparklines:
Step 1: Select the cells containing line sparklines;
Step 2: In the "Sparkline" tab from Ribbon, select a sparkline style from the Style section;
If you have Excel 2016 or earlier version, you will see the "Design" tab instead of the "Sparkline" tab.
Step 3: Click "Sparkline Color" to change the sparkline color;
Step 4: You can also change marker color by clicking "Mark Color";
Step 5: Mark specific points in the "Show" section, such as "High Point", "Low Point" etc;
For example, the "High Point".