The only likely cause of a true EMP is a nuclear detonation at high altitude. The effect would be instant destruction of virtually all unprotected electronics, including all but vintage vehicles.
I would expect that most of the population would perish within a few weeks, from want of food, water, medical attention, and probably from violence.
Without going into forbidden p0litical territory I think it safe to say that national and regional government would in effect cease to exist. How are they to govern over significant distances without modern communications and transport.
Basic very local government of a sort might survive.
No significant EMP event has ever occurred, though there is some evidence of relatively localised effects from early above ground atomic bomb tests.
I would thoroughly recommend the novel "one second after" as a fictional but IMO somewhat accurate account of an EMP attack.

A severe solar flare is a very different event, it would induce damaging electrical currents in long electrical conductors.
Long distance high voltage grid lines and equipment connected thereto would be the main casualties.
Also at risk would be other long conductors such as pipelines, telephone and telegraph cables, railroad lines, even long wire fences could have dangerous voltages induced that could start fires.
Physically small equipment if not connected to the grid should be fine, by "small" I mean anything that can be delivered or moved by a truck.
There might be no, or very severely rationed grid power for some years, but other electrical or electronic equipment should be fine.
A severe solar flare has previously occurred, but it was before the days of large grid systems.
Google the "Carrington event" for details.
A less severe event occurred some years ago and disrupted the electrical grid in Canada and parts of the USA,