Note: Only accounts set up via recovery phrase are provide with (and therefore able to see) a recovery phrase. For accounts created or imported with Google login, only private key will be available.
First, Open your Keplr extension and click on the profile icon in the upper-right corner.
Click on the three dots next to the selected account and in the drop-down menu select [View Recovery Phrase]. Confirm by inputting your password.
Once the Recovery Phrase is shown, you can copy it as needed.