[Feature Request] Add fullscreen / expand button to embedded content

[paulux84]

Is your feature request related to a problem?

Embedded content in Outline is currently displayed within a constrained area of the document.

For complex embedded content such as architecture diagrams, dashboards, interactive applications, or documentation, the available space is often insufficient for comfortable viewing and interaction.

Although some embedded providers support fullscreen natively, there is no consistent way to expand any embed directly within Outline.

Describe the solution you'd like

Add a Fullscreen / Expand button to embedded content, allowing users to view and interact with it using the entire screen without leaving the current Outline document.

Ideally:

• Display an expand/fullscreen icon when hovering over an embed.
• Allow the embed to occupy the full browser viewport.
• Support interactive embedded content, not just videos.
• Allow exiting fullscreen using Esc or a close button.
• Restore the original embed dimensions when exiting fullscreen.
• Make the functionality available in both reading and editing modes.

The fullscreen behavior should be managed by Outline itself, rather than relying on the embedded provider to implement its own fullscreen functionality.

Example use case

When embedding an interactive architecture diagram (e.g., LikeC4, diagrams.net, or similar tools), the diagram is often too complex to navigate comfortably within the document's limited width.

A fullscreen button would allow users to explore the diagram without opening a separate tab, maintaining the documentation context.

Additional context

This would significantly improve Outline's usability as a central technical documentation platform, particularly for teams embedding diagrams, dashboards, and interactive tools.