Type alias MutableTags

MutableTags: Omit<Tags, keyof (ExifToolTags & FileTags & ErrorsAndWarnings)>

Tags, minus the ExifToolTags, FileTags, and ErrorsAndWarnings, all of which aren't writable.

Note that this contains (many!) additional non-mutable fields--please check the ExifTool documentation to see which fields from which groups are writable for your given file type.