replace the submit input of a specific gravity form with a custom, extensively stylable button. This one is styled within Pro Theme, was inspired by this documentation: https://docs.gravityforms.com/gform_submit_button/#1-change-input-to-button-

functions.php

// 03. Change All Gravity Forms Buttons to Branded Button
// =============================================================================

add_filter( 'gform_submit_button_1', 'form_submit_button', 10, 2 );
function form_submit_button( $button, $form ) {
  return "
    <button class='button gform_button e21-23 x-anchor x-anchor-button' id='gform_submit_button_{$form['id']}' tabindex='0' style='outline: currentcolor none medium;'> 
      <span class='x-anchor-content'>
        <span class='x-graphic' aria-hidden='true'> 
          <i class='x-icon x-graphic-icon x-graphic-primary' aria-hidden='true' data-x-icon-s=''></i> 
        </span> 
        <span class='x-anchor-text'>Submit</span>
      </span>
    </button>
  ";
}

global.css

/* These styles are supplementary, incomplete */
.button, [type="submit"] {
	padding: 0.363em 1.125em 0.613em;
  font-family: "Poppins", sans-serif;
  font-weight: 700;
}
.button.e21-23.x-anchor, [type="submit"].e21-23.x-anchor-content {
  font-size: 1.08rem;
  text-shadow: none;
}