How do we programmatically place a section and then a block in that region on module install?
Put this code in an .install file:
// Create a Home web page with alias 'home'.
  $node = Node::create([
    'type' =&gt; '&lt;node_type&gt;',
    'langcode' =&gt; 'en',
    'uid' =&gt; 1,
    'title' =&gt; 'Home',
    'status' =&gt; 1,
    'path' =&gt; [
      'alias' =&gt; '/home',
      'pathauto' =&gt; PathautoState::SKIP,
    ],
  ]);

  // Variable to hold the sections for this node.
  // Defaulting to have a blank section first.
  $sections[] = new Section('layout_onecol');

  // Create a new section.
  $section = new Section('layout_onecol');

  // Config for the multi-type list block.
  $pluginConfiguration = [
    'id' =&gt; '&lt;block_id&gt;',
    'provider' =&gt; 'entity_block',
    'label_display' =&gt; FALSE,
    'view_mode' =&gt; 'default',
  ];

  // Create a new section component using the node and plugin config.
  $component = new SectionComponent($node-&gt;uuid(), 'content', $pluginConfiguration);

  // Add the component to the section.
  $section-&gt;appendComponent($component);

  // Add the section to the sections array.
  $sections[] = $section;

  // Set the sections.
  $node-&gt;layout_builder__layout-&gt;setValue($sections);

  // Save the node.
  $node-&gt;save();