When the numbers in a chart vary widely from data series to data series, or when you have mixed types of data (price and volume), plot one or more data series on a secondary vertical (value) axis. The scale of the secondary vertical axis shows the values for the associated data series. A secondary axis works well in a chart that shows a combination of column and line charts. You can quickly show a chart like this by changing your chart to a combo chart.

1. Select a chart to open Chart Tools.

2. Select Design -- Change Chart Type.

3. Select Combo -- Cluster Column - Line on Secondary Axis.

4. Select Secondary Axis for the data series you want to show.

5. Select the drop-down arrow and choose Line.

6. Select OK.

Support article: https://support.microsoft.com/en-us/office/add-or-remove-a-secondary-axis-in-a-chart-in-excel-91da1e2f-5db1-41e9-8908-e1a2e14dd5a9