As an admin, you can turn off multi-factor authentication. I've put this together specifically for people who might have signed up for a Microsoft 365 trial, or perhaps you've set up a tenant to run training with a group. With MFA off, users wont be prompted to provide a phone number or another authentication method when trying to sign in to their Microsoft Tools.
Sign up for a free trial to try out Microsoft 365 + Power Platform tools
With a free trial of Microsoft 365 you can use the Power Platform and Microsoft 365 tools without interfering with your normal work account. Useful for creating demos or for training.