The Checkout gives you the option to show/hide the Company field on your checkout page.
Here's how:
Step 1: Go to the 'Design' tab
Scroll down to the Checkout Form Fields and click on the “Shipping Address” field.
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Step 2: Locate the Company field
Choose to show/hide the company field by clicking on the eye icon placed beside it.
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Once done, click on the 'Update' button.
This will save the changes.
Here's how the company field will appear on the checkout page:
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Note: Similarly you change visibility of Company field for "Billing Address".
That's it! This is how you can add the company field in the shipping or billing address.