Dear USMAN AHMAD5,
Good day! Thank you for posting to Microsoft Community. We are happy to assist you.
As per the description you have shared, we understand that you want to send large size attachments within outlook email.
Typically, for Internet email account. such as Outlook.com or Gmail, the combined file size limit is 20 megabytes (MB) and for Exchange accounts (business email), the default combined file size limit is 10 MB, you can refer to Send large files with Outlook - Microsoft Support. If you need to send larger files, you can use OneDrive or SharePoint to share the file instead of attaching it to the email. This way, you can share files up to 100 GB in size. To use OneDrive or SharePoint, you can upload the file to your OneDrive or SharePoint account and then share the link to the file in your email. This will allow the recipient to download the file directly from OneDrive or SharePoint.
I look forward to your update. Please feel free to let me know if there are any questions or I've got you wrong. I will continue to assist you based on the information you provide. I sincerely appreciate your patience and cooperation.
Thank you for your precious time. Have a nice day.
Sincerely
Libeamlak | Microsoft Community Moderator