Start Process via API and parse variable values

I have an HTML page which contains an input field and a Submit button. The button contains a POST call to start my task with


My question now is, if it would be possible to fill out variables a form contains at the beginning of my Task, with the input from my Website?
Maybe with a JSON Body or something similar?

Thanks in advance
Patrick Unverricht

Yes you can, read here

Retrieves the start form variables for a process definition (only if they are defined via the Generated Task Form approach). The start form variables take form data specified on the start event into account. If form fields are defined, the variable types and default values of the form fields are taken into account.