In add custom field, cannot see dropdown data type list

Let me present some information about data type list in creating a custom field, @dinesh2.

In QuickBooks Online Plus and Essential, you can create a custom fields on your sales forms. However, if you are using this versions of QBO, then selecting the type of data is unavailable. This is the reason why you can't see the option in the page. 

Currently, you’ll be able to add up to three custom fields on the form. Here's how:

1. Select the Settings ⚙ menu, then choose Custom fields.
2. Click Add field.
3. Enter a name in the Name field.
4. Choose the All Sales forms checkbox.
5. If you want the custom field to appear on printed and delivered forms, enable the Print on form switch. Otherwise, it will only be visible in QuickBooks.
6. Lastly, click Save.
   
   

If there are still information you’d like to include, you might want to enter them on the Message on invoice field. You may consider checking out this article for more info: Customise invoices, estimates, and sales receipts in QuickBooks Online.

Keep in touch if you need additional question about managing your sales forms in QuickBooks. I'll be glad to help you more. Stay safe and have a good one.