Select your new hard drive from the left column in Disk Utility.

If the new drive is not showing up, disconnect the enclosure and check if the hard drive is properly connected to the enclosure.

Select the Erase option near the top row of buttons.

Select a name for your new drive, and select "APFS" for the format.

Warning: Pressing the erase button will erase the entire contents of the drive. Make sure you have selected the new hard drive!

Press the erase button.

This process may take up to 10 minutes, so be patient.

Quit Disk Utility once the erase is complete.