CSS changes on forms in Shopify Forms App

Shopify Apps
1

I would like to request some modifications for the forms in “Form App”. Specifically, I am looking for the following options:

  1. An option to change the font size of the form heading.
  2. The ability to modify the outline and placeholder color of the input fields.
  3. A column layout option for the form.

Please let me know how I can proceed with these changes.