This is built into Excel. Put your data in a table: Select the cells with the data (not the total) and press Ctrl+t, or go to the insert tab, and click Table. It should show the range of the data you have selected. If you have column headers for each column, check the box, if not leave it unchecked and Excel will name them for you. Click OK, and your data should appear in a banded table. Go to the Table Design tab at the top, and check the box next to Total Row. By default, this will show a total for the last column, but if you want to total any other column, just click in the cell in the total row of that column, and select how you want it aggregated. To add new rows, select the bottom right cell of the data, not the total row, the one right before it, and press <Tab>.
Here is a link to a webinar on working with tables for you to check out if you have time https://techcommunity.microsoft.com/t5/resources/modern-excel-webinar-working-with-tables-in-microso...
