What constraints are you using within that cell? If you re using a height constraint of 50 your image will always be 50.
You might want the image to be a specific size for each device (i.e 50,70 and 100 correspondingly). A way to go about this is make the image have a distance from the top, bottom and left side of the cell and give it a specific aspect ratio.
Then use the tableView delegate method to determine the size of your cell.
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
//if iphone 5 return x (e.g 50)
//if iphone 6 plus return y (e.g 100)
}
This way you re changing your cell size ( which im guessing you need to be smaller if your image is smaller and bigger if your image is bigger ) and your image auto resizes automatically using the constraints mentioned above