The HTML placeholder attribute is only styled/colored via CSS.

If you want to remove the placeholder and put text outside of the field, be aware that it will require more screen space so you will need to address layouts for mobile screen sizes. You can put the text outside by manually editing the template and reworking all of those form fields.
The move to using the modern placeholder approach was done a few versions back. You could use some much older templates as a reference for how to put the "field is required" text outside the field, but will have to work on styling it yourself because there wasn't much in those older templates for styling it for mobile devices at that time.