You can add a group of fields to your checkout using the Checkout UI extension. This lets you collect information for the entire order, not just for individual products. This feature is available on the Growth plan for stores using Shopify Plus.
From your Shopify admin, go to Settings > Checkout.
In the Configurations section, click Customize next to the checkout you want to edit.
At the top menu bar, select the checkout page where you want to add the app.
Click Add app block.
Click on the Magical Fields app block.
Enable Allow app to block checkout.
Click Save.
After adding the app to your checkout, you can move it to your preferred checkout area.
That’s it. Your custom fields are now part of your checkout.