You can also achieve this by using the QUERY function in Google Sheets. Create a separate sheet where you generate the dropdown values based on the values in the first column. Then, use the QUERY function in the second column to fetch the dropdown values dynamically.

Another approach is to use Apps Script, Google's JavaScript-based scripting platform. You can write a custom function that uses the onEdit trigger to update the dropdown menus in real-time. This way, whenever a value in the first column changes, the second column's dropdown menus will automatically update.

One way to achieve this is by using the Data Validation feature in Google Sheets. You can create a list of values in one column and then use the INDIRECT function in the range field of the data validation settings for the second column. This way, the dropdown menus in the second column will dynamically update based on the selected value in the first column.