is there a proper way to compress image

Question

#This is the function from which i select multiple image from gallery and add it to my own list that is imageFileList

  final ImagePicker imagePicker = ImagePicker();
  List<File> imageFileList=[];
  String images;
  void selectImages() async {
    List<XFile> selectedImages = await imagePicker.pickMultiImage(imageQuality:5);
    if (selectedImages != null) {
      for(int i=0;i<selectedImages.length;i++) {
        imageFileList.add(File(selectedImages[i].path));
      }

#everything works fine but the problem is that i want to compress. Meaning the image which i pick from gallery first i want to get its size and if its size is greater than 40mb or 20mb or 15mb.. then i want to reduce to 5 mb or even to kb by keeping the quality of image and if the image is already in kb i dont want to compress it. i want to achieve it something like this but i am little confused on how to achieve that and add it to my imageFileList. Need some help thanks in advance