As store owners may concern, you cannot set minimum quantity for configurable product in Magento 2. So I recommend a new extension called Magento 2 Minimum Quantity of Configurable Product.
This extension is quite simple to configure and also has reasonable price for its amazing feature: set minimum quantity for specific or all configurable products as wish. In addition, the module can show error message when customers don’t meet the quantity requirement.
Here is an example:

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