"You can find a list of required documents and items on the official EU website for product directives and regulations. However, this requires that you know which directives and regulations (e.g. Low Voltage Directive) apply to your product.
Fortunately, you can use services such as ProductIP.com to confirm applicable regulations, and thereby the list of required technical file documents."
Read more at: https://www.compliancegate.com/technical-file/