I don't think you'd be able to do this out of the box but one configuration of a promotion rule to try would be to give 100% discount on a product with the condition being that this can only be applied once and if the cart is over $100.
Alternatively, you're more likely to be able to achieve more complex promotions with an extension from the marketplace. For example, this one from Amasty https://marketplace.magento.com/amasty-module-special-promotions-pro.html
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