add_wp_admin_styles.php

// Add inline styles to WP admin
add_action('admin_head', 'colorpicker_styles');

function colorpicker_styles() {
    echo '<style>
    .wp-picker-container .iris-picker {
        height: 50px !important;
        padding-top: 15px;
    }
    
    .iris-picker .iris-palette {
        width: 25px !important;
        height: 25px !important;
        margin: 0 5px 5px 0 !important;
    }
    
    .wp-picker-input-wrap .cmb2-text-small,
    .iris-picker-inner,
    .my-color-field {
        display: none !important;
    } 
  </style>';
}