A WordPress plugin that contains many blocks to build your RundizStrap theme, or you can use it with any Bootstrap 5 themes.
You can manually set CSS class(es) by referring to the Bootstrap document.
Supported custom HTML attributes like <code>data-*</code>, <code>aria-*</code> in most blocks.
Available blocks:
<ul>
<li>Customizable div</li>
<li>Layout container</li>
<li>Layout row</li>
<li>Layout column</li>
<li>Search (for navbar and anywhere else)</li>
<li>Pagination (for list posts)</li>
<li>Navbar container</li>
<li>Navbar toggler button (for responsive toggler)</li>
<li>Navbar responsive wrapper (collapse, offcanvas)</li>
<li>Navbar navigation (display menu items)</li>
<li>Button (link, or button)</li>
<li>Comment form</li>
<li>Post navigation (display next, previous post)</li>
</ul>
Tested up to PHP 8.5.
The original source code is on GitHub ( https://github.com/Rundiz-WP/rundizstrap-companion ). 
It contains the original source of blocks before compile/build and blocks that are already built, the build tools via Node package (package.json).

RundizStrap Companion

A plugin that contains blocks for the Bootstrap theme that help you customize your site in your style. All blocks are based on Bootstrap CSS.

Andy Brudtkuhl

Enqueues a stylesheet that adds Bootstrap styles to Gravity Forms forms.

RundizStrap Companion vs Bootstrap Gravity Forms