The code of the attribute is tare_weight.
If you want an age verification prompt, you will need to create this attribute in the backend of the POS.
Go to Items in the main navigation menu.
Press Custom Attributes in the upper right corner.
Press + New Product Attribute.
Under ATTRIBUTE CODE, enter tare_weight.
Under ATTRIBUTE NAME, enter Tare Weight.
Under CUSTOM ATTRIBUTE TYPE, select Floating point number.
Under FRONTEND INPUT TYPE, select text.
Under UI COLUMN SIZE IN POS, enter 3.
You can leave the dropdown menu under SHOW ON QUICK UPDATE FORM blank.