Hi, BN-
Welcome! One of Excel's fundamental features performs that task for
you. If you'll copy your formula cell (on the menu, click Edit
Copy), move the cell pointer to the next line, and click Edit Paste, the formula from the original cell will paste into the new cell *and* adjust for cell references.

Another way to perform this is to land the cell pointer on the formula
cell. Notice the cell is outlined in black with a little square in the
lower right corner. When you roll the mouse slowly over that square
the cursor will change from a white cross to black crosshairs: right
click, and drag the mouse downward (or across, but not in this case)
and the original cell copies into the new cells, adjusting cell
references all the while.