Where can I read more about this in short-form (not a college Politics textbook).
but to help maybe you can corroborate the following:
there is an ancestral lineage to the founding documents and frameworks of countries, with branches also connecting and merging
most countries in the form and shape that we know them today have had a major revision in or replacement of their constitution over the last 100 years. so even though people say the US is "young", many old world countries are younger or are operating under a framework which is much younger
when people say the US has been exporting democracy, this would be true. The US has a habit of creating temporary vassal states without really taking any resources or expanding its territorial boundaries, thats kind of new on the world stage, and in parallel the concepts have been inspirational to other states.
and of course its not all related to the US and supernational institutions as it all evolves in parallel, but they do all influence each other.
The Swiss patched theirs after a comparatively small physical fight for direct democracy at the federal level.
The US contains representative democracy over concerns about the speed of communication over a long distance, even though they were referring to 13 states on the east coast in 1780 (admittedly the western borders of those states were practically infinite), Switzerland is not that large and would fit inside of Pennsylvania so the rationale against direct democracy could not be maintained, but as they learned, representative democracy is too convenient for a central organization to relinquish and direct democracy is a threat to it. The people of Switzerland won though, and good for them.
The federal government in Switzerland does grow, but very slowly and the loose confederation has an understanding that any canton can make a law and it is honored simultaneously by all the other cantons and inherits the brand of Switzerland. It could get complicated with conflicts of law but it doesnt because the reality is not that much happens.
Feel free to correct anything inaccurate.