Can we render the Tiny MCE 5 toolbar menu items horizontally of a specific menu button?

Question

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Can we render the menu items(Menu Item1, Menu Item 2, and Toggle menu item) horizontally without overriding the CSS of the tox-collection__group class?

Is there any way to use custom css classes for tiny MCE styling?

Thank you in advance

As far as I checked the documentation, I haven't found anything regarding passing custom css classes. May be I am missing something or it is not possible.