Amplify studio - setting onclick handler for button and select items dynamically

I have a form with few text fields, I have a button at the bottom. I want to collect all the information from the text field when the user pressed the button. I want to set the onClick handler for button in amplify studio to collect all the information in the text fields and invoke an api. Is it possible to do this ?

I have a drop down component in the form, how do I populate the drop down items dynamically in amplify studio ?