I want to add button/option in action menu on record view

Hi,

I want to add a custom button/option in action menu on record view.

E.g. On Accounts main view/list view, there should be a button in the action menu named as "summarize" and clicking on which It should only show the few fields from that record. like name, description only.

I am able to create the action button using studio and its visible in the view,
BUT i also want to see If same could be done using the code.

And secondly the custom view triggering and the minimalistic fields on that custom view.