You may want to create a drop down list in Google Sheets using data that is already in your spreadsheet. This data could change from time to time, and the values in the drop down list will change with it.
A drop down with dynamic values can be created in just a few steps. Select the cell(s) that you want the drop down to be in and then go to the Data menu and then Data validation. Keep in mind that some newer spreadsheet programs have a built-in drop-down data type.
Once the Data validation box pops up, choose List from a range. This is where you will select the range that holds the values that you want for the drop down.
Insert your cursor in the box to the right of List from a range and then highlight the range of cells that contain the values that you need.
To select cells that are not next to each other, just type the cells or cell ranges in separated by commas.
When you get back to the Data validation window, the range that you selected will be pre-filled in the Cell range box of the Data validation pop-up window.
Click Save and your drop down box with dynamic values is complete.