pack.mcmeta is located in the root of the pack. Before 1.21.9, the version is written as one number in pack_format - for example, for 1.20.1:

{
  "pack": {
    "pack_format": 15,
    "description": "Мой пак"
  }
}

Since 1.21.9 there is a pair instead min_format and max_format: from what version and up to what version does the pack work. Number - major format; minor (fractional part, as in 97.1) is written in pairs [97, 1], and the bare number in max_format means "any minor". Resource pack for 26.3:

{
  "pack": {
    "min_format": 97,
    "max_format": 97,
    "description": "Мой пак"
  }
}

The date pack for 26.3 is the same with its number:

{
  "pack": {
    "min_format": 121,
    "max_format": 121,
    "description": "Мой пак"
  }
}

The pack, which should work on older versions, writes both methods at once: pack_format for the old ones and a couple for the new ones. Between them, from 1.20.2 to 1.21.8, there was also supported_formats - a list of suitable numbers. If the number doesn't match the game version, the pack burns red on the list, but most often works; you can change the number in someone else's package. pack converter.