Mindmaps are tools that facilitate visual brainstorming and organization. There are a variety of free and paid sites that offer the tools and examples to use as template. Here are a few that allow collaboration.

GitMind - https://gitmind.com/ - free, with over 100 templates that you can adapt. Google Chrome and App extensions are available. Examples include project management, process plans, organization, site maps, study plans and many more.

Whimsical - https://whimsical.com/ - collaborative tools that combines whiteboards, wikis, diagrams, sticky notes, flowcharts and docs. Free for up to 3,000 items per workspace with limitations on members, or paid plan for more.

Coggle - https://coggle.it/ - similar to GitMind. Easy to edit due to built-in context menus. Basic version is 3 (for 3 private diagrams and unlimited public ones). Pay for more features.

Richard Byrne has a good post on different tools available at this link: https://www.freetech4teachers.com/2021/08/fifteen-tools-for-creating-mind-maps.html