Not an attempted coup d'etat, as many are saying in the media.
I must credit Juan Cole with making aware of this useful term, which apparently comes out of Latin America. According to Cole, a coup attempt traditionally involves military and also is directed at overthrowing a leader in power. What happened yesterday in the Capitol did no fit either of these criteria.
But it does fit an autogolpe very well. This is a self-coup, if you well, a situation where a leader, especially one who is about to be removed from office, acts to overthrow the established rules to remain in power, usually assuming authoritarian power in doing so. This certainly looks like what Trump was trying to do, but failed to achieve. So it was an attempted autogolpe.