Microsoft Exchange email is easily set up on your iOS device. You can choose the default Mail app on your phone, or for more features, the Microsoft Outlook app is a popular choice. In fact, there are several apps that will work with your Microsoft 365 Exchange account, so this really comes down to personal preference.
This article explains how to setup your hosted Exchange email account with your iPhone or iPad. The screen shots are taken from an iPhone running iOS version 13 in dark mode, however the process is not hugely different for older versions of iOS.
1. Go to Settings > Passwords and Accounts
2. Choose Add Account
3. Choose the Exchange Option
4. Enter your full email address in the email field.
5. Choose a name for your account. This is a personal reference only.
6. You will be presented with a message asking you to sign in to your account. Choose the option to 'Sign In'.
Logging in with your email address and password will validate the account and give you the option to set up your Mail, Contacts, Calendar and Notes. Choosing all of these options is recommended so your phone has access to the same information you would see on your desktop device.
If you're asked for any manual server settings, such as the server name, please enter:
outlook.office365.com
It should not be necessary to add a domain name, and if asked for your user account, this will be the same as your email address.