How to Add Multiple Footer Columns in the Main Area Footer?

After you have set the Main Area Footer Layout, you can now add footer content for the main area footer section. To do that,

Open your theme customizer after navigating to Appearance >> Customize.
Click on Widgets.
Based on the chosen Main Area Footer Layout, select Footer Column 1, 2 , 3 or 4 accordingly.

Add your footer content by clicking on the + button to add blocks for different footer columns.

Adding Paragraph block to Footer column1

Below is an example of Main Footer where 4 footer columns have been implemented.