Folk guitar, how to play several strings at the same time

If you want to play 1235 strings, then use the ring finger, the middle finger, the index finger and the thumb to strum them. Generally speaking, the thumb is responsible for the 456 strings, and the middle and index fingers are responsible for the 321 strings. But it is not absolute, sometimes the bottom three can be moved up according to the need to play, easy to play. And if there are numbers on all six strings as in "Those Years", you can sweep down, but it is not the same as a traditional sweep.