You can try the Data Source for contact form 7 ( https://wordpress.org/plugins/cf7-data-source/ ). It includes a pair of additional controls, Recordsed, to get the data from different data sources, like a database, a CSV file, a JSON structure, and other alternatives, and the RecordSet Field Link control that allows you to connect the form fields, like the DropDown field with the RecordSet to populate the first one with the information obtained from the data source.
You can find multiple functional examples in the following link: