Here’s an organization that studies and categorizes Coup d’État against a specific set of criteria.

Here is their statement about Jan 06.

That statement provides links to their methodology and dataset, as well as other details.

Here is an excerpt:

The Cline Center’s Coup d’État Project is the world’s largest global registry of failed and successful coups. The Cline Center defines a coup as an “organized effort to effect sudden and irregular (e.g., illegal or extra-legal) removal of the incumbent executive authority of a national government, or to displace the authority of the highest levels of one or more branches of government.” To be categorized as a coup, an event must meet the following criteria (which are detailed at greater length in the Coup d’État Project codebook):

-There must be some person or persons who initiated the coup.

-The target of the coup must have meaningful control over national policy.
-There must be a credible threat to the leaders’ hold on power.
-Illegal or irregular means must be used to seize, remove, or render powerless the target of the coup.
-It must be an organized effort.

Summary

Using the Cline Center’s Coup d’État Project definitions, the storming of the US Capitol Building on January 6, 2021 was an attempted coup d’état: an organized, illegal attempt to intervene in the presidential transition by displacing the power of the Congress to certify the election. In terms of the type of coup attempt, the complex nature of this event leads it to be categorized as both an attempted auto-coup and as an attempted dissident coup, reflecting the separate activities of distinctive actors involved in the event.