Reuse/sync view mode display settings across entity bundles?
Multiple solutions, pick what works best for you..

View modes

If you really want to work with view modes, there might be ways to copy the settings around between bundles. This still leaves you with lots of redundancy. So maybe not the preferable solution.

Views fields

If you work with Views, you can use views fields instead of view modes. These have their own advantages and drawbacks. You cannot use a layout (afaik). And now you cannot reuse the fields configuration across views.

So..


views fields: reuse across entity bundles, but not across views.
view modes: reuse across views, but not across entity bundles.


Ctools content panes / panels

Panels configurations can be reused in different places.

I personally do not use them as much, so I am sure someone else could write more about it.

Entity display plugin / Renderkit.

You can use EntDisP, to configure an entity display from multiple components. (This is using components from Renderkit.)

The module gives you a views row plugin, and a views field handler. So you can create an "entity display" for the entire row, or you can combine it with views fields.

It also gives you field formatters for entityreference, taxonomy term reference, paragraphs, and field collection.

You can configure the entity display in the place where you use it, so it will be stored as part of the view, field formatter, etc.

Or you can configure it as a "preset" with CFR Preset, so it will be stored independently and can be reused in different places. Such presets can be exported as features.

You can embed view modes in entity displays.

You can also embed entity displays in view modes using EntdispFieldUI.