This method will guide you to concatenate data in each column with the Alt + Enter by a formula in Excel. Please do as follows:

1. Select a blank cell you will place the concatenation result, type the formula =A1 & CHAR(10) & A2 & CHAR(10) & A3, and drag the AutoFill Handle right to other cells as you need.

Note: In the formula =A1 & CHAR(10) & A2 & CHAR(10) & A3, A1, A2, and A3 are cells you will concatenate.

2. Keep the formula cell selected, and click Home > Wrap Text.

Now you will see each column is concatenated with Alt + Enter. See screenshot:

With Kutools for Excel’s excellent Combine feature, you can also concatenate data in each column with Alt + Enter by several clicks in Excel. Please do as follows:

1. Select the columns you will concatenate, and click Kutools > Combine. See screenshot:

2. In the Combine Columns or Rows dialog box, please:
(1) Check Combine rows option in the To combine selected cells according to following options section;
(2) Check the New line option in the Specify a separator section;
(3) Check one of options as you need in the Options section. In my case, I check the Delete contents of combined cells option;
(4) Click the Ok button.

Now you will see data in each column is concatenated with Alt + Enter. See screenshot:

How to concatenate keeping number/date formatting in Excel?