I followed the instructions to increase the attachment size as shown here: https://www.microsoft.com/en-us/microsoft-365/blog/2015/04/15/office-365-now-supports-larger-email-messages-up-to-150-mb/
Its been a couple of days since I waited for the changes to go in but I still notice the issue: The following files weren't attached because adding them would cause the message to exceed the maximum size limit of 34 MB
What else I can do to increase the size of the attachment?
Based on the questions - I tried it on OWA with an existing mailbox.