QuickBooks Online (QBO) has a maximum number of characters you can enter in each field. You can refer to this article and proceed to What are the character limits in fields section for more information: QuickBooks Online file size and feature limits.
If you already reached the maximum limit, the option to extend it is currently unavailable.
I can see how this option would be helpful for you, and I'll take note of this. Our Product Developers are always looking for ideas from users on how to improve QBO.
In the meantime, I recommend visiting our Blog site. This is where we share recent happenings and future developments, such as updates to newly added features.
Leave a comment below if you have any other questions or concerns. I'm more than willing to help. Have a good one!