To create a signature with multiple lines in Outlook, you need to ensure that the signature editor is set up correctly. When creating or editing your signature, you should be able to use the Shift + Enter key combination to add a new line within the signature. This allows you to include additional information such as your email and phone number on separate lines.
If you are still unable to add multiple lines, it might be worth checking if there are any restrictions or issues with the current version of Outlook you are using. Additionally, ensure that you are not using any special characters that might interfere with the signature formatting.
References: