The TYPO3 extension ses_mailer is a configuration helper for sending mails from TYPO3 with AWS SES.
Install this extension via composer:
composer require different-technology/ses-mailer
Open the TYPO3 backend or Install Tool, click on "Settings" and choose "Extension Configuration".
Select "ses_mailer" and insert your AWS access key (with permissions to use SES).
You can find more details here: https://markus-code.com/2021/03/typo3-emails-with-aws-ses-mailchimp-and-more/