Greg-Boggs

<?php
function lib_layouts_entity_view_mode_alter(&$view_mode, EntityInterface $entity, $context) {
  if ($entity->getEntityTypeId() == 'node' && $entity->bundle() == 'landing_page' && $view_mode == 'full') {

    if ($entity->hasField('field_layout')) {
      $field = $entity->get('field_layout');
      if (!$field->isEmpty()) {
        $layout = $entity->get('field_layout')->getString();
        $available_modes = \Drupal::service('entity_display.repository')->getViewModes('node');
        if (array_key_exists($layout, $available_modes)) {

StevenGFX

View

This accepts views arguments as well:

{{ drupal_view('who_s_new', 'block_1') }}

View with multiple arguments:

{{ drupal_view('who_s_new', 'block_1' 'contextarg1', 'contextarg2', '...') }}

BBGuy

<?php

// Basics
// Get a value.
$value = $wrapper->field_x->value();
// If the field is a reference field you will get the field object
// To get the wrapper back use:
$wrapper_b = $wrapper->field_ref;

// To set a value.