It depends on the state one lives in the USA. For instance in Texas, a garage inspects your vehicle once a year on basic functionality for it to qualify for a sticker one puts on the windshield (automatic ticket if law enforcement stops you with one out of date). In California, one has to get a smog inspection every so often to qualify for the sticker on the license plate to indicate one has paid one's vehicle tax for the year (automatic ticket if stopped by law enforcement with expired sticker).
Here in Idaho traditional ICE vehicles need emissions testing every few years after a certain age, but hybrids, PHEV’s and BEV’s are exempt. No other inspection required to renew your tags every year.
They measure exhaust fumes with a special nozzle that fits over your exhaust pipe(s) while your vehicle is idling and I think with a dynometer(it's been a while for me) and there is a maximum output of various gases. If your vehicle is over the limit, it must be fixed to be below the maximum before one is eligible for a passing certificate which is sent electronically to the Department of Motor Vehicles.
I haven't lived in Texas in 20+ years but I remember the annual sticker visits at gas stations, they would check that the head lights worked and were pointed at the correct direction for the height of the lamp, that your windshield wasn't cracked in your field of view, the using the brakes turned on the brake lights, and other things, if your vehicle failed any of the checks you were required to fix them and get re-inspected and pass the entire suite of tests before one got the inspection sticker.
