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If you will use the "Address" field found under the "Quick Tools" section, there's no option to validate the value of the zip/postal code.
If you'll use a simple text box, that allows you to set or impose a validation type and an input mask, you can also set max size and a default value. You can also use conditional logic to check if the value inputted is valid in your own terms.
We also have widgets related to geolocation or postal codes. Here are some of them:
I hope that helps.