[Extensibility Request] Allow extending available font sizes in RichContent editor (sizes 5-7) #8368

We are using the standard Business Central RichContent control:

field(IAX_HTMLContent; IAX_HTMLContent)
{
ExtendedDatatype = RichContent;
MultiLine = true;
}

The RichContent editor currently exposes only a limited number of font sizes through the toolbar.
For several customer scenarios, especially document templates and formatted public-sector communication, lower font sizes are required.
We would like to request an extensibility point that allows partners to extend or override the list of selectable font sizes.

Requested extensibility
Allow extensions to:
Add custom font sizes
Extend the default font-size list
Override the default list completely

Example:
Current: 1, 2, 3, 4
Requested: 1, 2, 3, 4, 5, 6, 7

Reason
The RichContent editor is a standard Microsoft control.

Without an extensibility point, partners must either accept the limitation or replace the editor with a custom solution.
An event or similar extensibility mechanism would allow partners to support additional font sizes while continuing to use the Microsoft standard control.

Business value
Keeps customers on the standard RichContent implementation
Reduces need for custom editors
Improves partner extensibility
No impact on existing customers
Fully backward compatible

Additional information
This request originates from Microsoft Support case:
TrackingID#2610271420001478
Microsoft Support recommended opening a GitHub request for an event/extensibility point.