post_grid_layout_element_option_{id} used to render options output for each element on layout editor, where  {id} should replace with element id, like title, excerpt, and etc

 

Sample code for excerpt 

add_action('post_grid_layout_element_option_excerpt','post_grid_layout_element_option_excerpt');
function post_grid_layout_element_option_excerpt($parameters){

    $settings_tabs_field = new settings_tabs_field();

    $input_name = isset($parameters['input_name']) ? $parameters['input_name'] : '{input_name}';
    $element_data = isset($parameters['element_data']) ? $parameters['element_data'] : array();
    $element_index = isset($parameters['index']) ? $parameters['index'] : '';

    $char_limit = isset($element_data['char_limit']) ? $element_data['char_limit'] : 0;

    $css = isset($element_data['css']) ? $element_data['css'] : '';
    $css_hover = isset($element_data['css_hover']) ? $element_data['css_hover'] : '';


    ?>
    <div class="item">
        <div class="element-title header ">
            <span class="remove" onclick="jQuery(this).parent().parent().remove()"><i class="fas fa-times"></i></span>
            <span class="sort"><i class="fas fa-sort"></i></span>

            <span class="expand"><?php echo __('Post excerpt','post-grid'); ?></span>
        </div>
        <div class="element-options options">

            <?php


            $args = array(
                'id'      => 'char_limit',
                'css_id'      => $element_index.'_char_limit',
                'parent' => $input_name.'[excerpt]',
                'title'       => __('Word limit','post-grid'),
                'details'  => __('Set word limit.','post-grid'),
                'type'    => 'text',
                'value'       => $char_limit,
                'default'     => '',
                'placeholder'     => '20',
            );

            $settings_tabs_field->generate_field($args);


            $args = array(
                'id'      => 'css',
                'css_id'      => $element_index.'_css',
                'parent' => $input_name.'[excerpt]',
                'title'       => __('Custom CSS','post-grid'),
                'details'  => __('Set csutom CSS.','post-grid'),
                'type'    => 'textarea',
                'value'       => $css,
                'default'     => '',
                'placeholder'     => '',
            );

            $settings_tabs_field->generate_field($args);

            $args = array(
                'id'      => 'css_hover',
                'css_id'      => $element_index.'_css_hover',
                'parent' => $input_name.'[excerpt]',
                'title'       => __('Hover CSS','post-grid'),
                'details'  => __('Set hover custom CSS.','post-grid'),
                'type'    => 'textarea',
                'value'       => $css_hover,
                'default'     => '',
                'placeholder'     => '',
            );

            $settings_tabs_field->generate_field($args);

            ob_start();
            ?>
            <textarea readonly type="text"  onclick="this.select();">.element_<?php echo $element_index?>{}
.element_<?php echo $element_index?> a{}</textarea>
            <?php

            $html = ob_get_clean();

            $args = array(
                'id'      => 'use_css',
                'title'       => __('Use of CSS','post-grid'),
                'details'  => __('Use following class selector to add custom CSS for this element.','post-grid'),
                'type'    => 'custom_html',
                'html'    => $html,

            );

            $settings_tabs_field->generate_field($args);

            ?>

        </div>
    </div>
    <?php

}

Screenshot

View post on imgur.com

Also, check

post_grid_layout_elements