Most modern devices should support x265 playback which has the compression sizes you are looking for.

In addition to setting the cap to file sizes for media, you can also blacklist tags like REMUX etc.

This is an example of a custom format for hevc/x265 files that are no larger than 6Gigs. You just need to create a new custom quality profile and give below custom format a positive/higher score.

{
  "name": "Minima",
  "includeCustomFormatWhenRenaming": false,
  "specifications": [
    {
      "name": "No mo than 6 Gigs",
      "implementation": "SizeSpecification",
      "negate": false,
      "required": true,
      "fields": {
        "min": 0,
        "max": 6
      }
    },
    {
      "name": "1080p",
      "implementation": "ResolutionSpecification",
      "negate": false,
      "required": true,
      "fields": {
        "value": 1080
      }
    },
    {
      "name": "eng",
      "implementation": "LanguageSpecification",
      "negate": false,
      "required": false,
      "fields": {
        "value": 1
      }
    },
    {
      "name": "Preferred x265",
      "implementation": "ReleaseTitleSpecification",
      "negate": false,
      "required": false,
      "fields": {
        "value": "[xh][ ._-]?265|\\\\bHEVC(\\\\b|\\\\d)"
      }
    }
  ]
}