Hi, I'm John! I will help you with this.
Before blocking them, could you please check if those emails have an “Unsubscribe” or similar link at the bottom of the message? Legitimate newsletters usually include that option, and using it is often the most effective way to stop them.
If there’s no unsubscribe link, you can block them in Outlook. Microsoft has a support article that walks through how to block or unblock senders in Outlook. You can see it here: https://support.microsoft.com/office/block-or-unblock-senders-in-outlook-9bf812d4-6995-4d19-901a-76d6e26939b0
Let me know if you have any further questions or concerns.