The first CC occurred during the late 1780s and its when state legislatures sent delegates to Philly to establish the layout of the US government while working on the Constitution.
I dont believe a federal-level CC has ever convened (state-level CCs happen occasionally) except for the one time in the 1780s however in the midst of a real Constitutional crisis then a CC might happen (guessing unless someone else knows).
https://www.theconstitutional.com/blog/2019/09/04/constitutional-convention
https://courses.lumenlearning.com/wm-ushistory1/chapter/the-constitutional-convention/
The first CC occurred during the late 1780s and its when state legislatures sent delegates to Philly to establish the layout of the US government while working on the Constitution.
https://www.theconstitutional.com/blog/2019/09/04/constitutional-convention
https://courses.lumenlearning.com/wm-ushistory1/chapter/the-constitutional-convention/