That would be my no 1 go-to, if I didn't have to remain alert for my 3 year old sleeping next door (he can seep through the noisy neighbors though!)... (btw our neighbours are underneath and they cook at night, and talk very loudly)
Ear plugs should reduce intensity of sounds across the board. Yes, they’re less effective against low frequency noise, but reducing the intensity any amount goes a long way – the logarithmic scale is real!
I also personally find high frequency noise to be more disruptive: a car speeding by making wind noise is a lot worse than a large truck rumbling by slowly. Lower frequency is lower energy, after all