Is there is any option to add field in inventory section like no of pieces in each master carton product weight size etc....?

A warm welcome to the Community, usertariq.

The option to add additional fields in the inventory section is currently unavailable in QuickBooks Online. As a workaround, you can look for a third-party application that offers this functionality.

Here's how:

1. Log in to your QuickBooks Online account.
2. From the left pane, click on Apps.
3. Search for apps in the search box.
   

QuickBooks displays the list of applications available that matches the description you entered. Once you find the right app, click on it to open. 

We’re working on releasing new features soon. For product updates, you can check out our blog post for recent changes.

In case you need ideas on how to customise and utilise your sale form templates in QuickBooks Online, you can go through this article: Customise invoices, estimates, and sales receipts in QuickBooks Online. This will give you steps on how to add fields as well as changing the colour scheme.

If you have any other questions or need further assistance with this topic, let me know in the comment below. I'll be more than happy to help you anytime.

@usertariq 

You may need an inventory management app