If you do not have downloaded the MacOS installer of the version you wanted earlier, now you can use OpenCore to do so.

You can select Create macOS Installer to both download and create the USB installer for your selected version.

You might get prompted to insert your Mac password to finish the download.

If you choose to use OpenCore Patcher to create the USB installer, your drive will be formatted before it create the installer. If you do not want to format it, use the terminal command in Step 6.