how to create and save text to insert in documents

Hi, I'm John! I will help you with this.

Can you confirm if you see Mail template in the Message ribbon? Also, are you trying to use this saved text for emails only, or for Word documents as well?

I noticed this was posted under Outlook for Windows, specifically New Outlook.

You can create saved text using Mail Templates:

• Open New mail, then type the content you want to save. You can include the message body, recipients, subject, and attachments if needed.
• Then go to the Message ribbon and select Mail template > Save email as template. Enter a name for the template, then select Save.
• To view your saved templates, open Settings, then go to Mail > Templates. The saved templates should be listed by account.

For full guidance, please see https://support.microsoft.com/en-us/outlook/create-email-templates-in-outlook