Thanks for chiming in on this thread, FredyB.

For now, the Markup feature in QuickBooks Online is used only on the billable expenses for vendors. While the option to add a Markup column on estimates is unavailable, I recommend sending a product suggestion by going to the Gear > Feedback. Your request will be forwarded to our Product Development Team for review.

To check on the latest news and feature updates, please visit our QuickBooks Blog. 

If you require additional information or you have other concerns, please let me know in the comments below. Take care and stay safe!