A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Dear Ajith Varghese_AV,
Good day! Thank you for posting to Microsoft Community.
We are sorry to hear that you’re having trouble with SharePoint callout content width. I deeply understand the inconvenience caused and apologize for it.
This forum mainly focuses on Microsoft 365 and Office built-in features. However, from my research, it seems that the content width should be specified in pixels, with values between 240 and 610 pixels. Since my team and I don’t have sufficient resources and knowledge with this issue, I sincerely recommend you post your concern to the specific channel: SharePoint Development - Microsoft Q&A. Members and engineers over there are proficient in these issues. We are sure that our experts from that team can address your query effectively and accurately.
Once again, I apologize for the inconvenience this has caused. We appreciate your patience and understanding and thank you for your time and cooperation.
Sincerely,
Ralph | Microsoft Community Moderator