Install
This is the repository archive. It installs, but the folder name will carry the branch suffix and updates will not flow.
Install straight from GitHub with WP-CLI:
wp plugin install https://github.com/displaynone/wordpress-widget-bootstrap/archive/refs/heads/master.zipNo built-in updater. New versions won't appear under Dashboard → Updates. Install new releases yourself, or let Git Updater track the repository.
WordPress Widgets Bootstrapfy
Allows to add extra content (Bootstrap classes) to any WordPress widgets.
It adds a new input in every widget asking for bootstrap css and wrap the HTML widget into a new DIV

Instalation
- Download, install and active the plugin
- Modify the widgets in Appearance > Widgets
More information in the original post in Sentido Web (in Spanish)