liaison

The Collexpander WordPress plugin allows you to hide or show selected text content dynamically with a toggle button. 
It’s useful when you want to display long descriptions, FAQs, technical documentation, or additional product details without overwhelming the reader.
Simply insert the shortcode pair in your post or page:
[collexpander-show-content] 
  
[collexpander-hide-content]
Everything placed between the two shortcodes will be initially hidden, and can be expanded or collapsed when the visitor clicks the toggle button.
The plugin includes three customizable button styles (default, outline, and minimal) and two button text options (e.g., “Show” / “Hide” or “More” / “Less”). 
You can also easily adjust button labels, colors.
This plugin helps improve content readability and provides a clean, user-friendly experience — ideal for blogs, product pages, FAQs, and educational content where text organization and clarity matter.

collexpander

The Collexpander WordPress plugin allows you to hide or show selected text content dynamically with a toggle button.

Robert Noakes

Adds functionality to collapse and expand nav menus within the WordPress admin. All parent nav menu items are collapsed by default, but you have the option to store the collapsed/expanded state for the menus on a user-by-user basis.
<a href="https://noakesplugins.com/kb/nav-menu-collapse/" rel="nofollow ugc">View the Knowledge Base »</a>

Nav Menu Collapse

Simple, to the point, this should absolutely be in core.

Adds functionality to collapse and expand nav menus within the WordPress admin.

collexpander vs Nav Menu Collapse