Custom DeviceSize class template which creates a scale of 21 sizes based on a scale (in this case, the Silver Ratio).

DeviceSize.swift

import SwiftUI

class DeviceSize {

    var scale: [CGFloat] {
        var silverRatioArray: [CGFloat] = [0]
        for i in 0 ... 21 {
          if i > 1 {
            silverArray[i] = silverArray[i - 1] * (1 + sqrt(2))
          } else {
            silverArray[i] = 1
          }
        }
        return silverRatioArray
    }
    
    var size: [CGFloat] {
            let displayFactor: CGFloat = 420
            var scaledArray: [CGFloat] = [0]
            for i in 0 ... 21 {
                size[i] = displayFactor * scale[i]
                if i < 21 { size.append(size[i]) }
            }
            return scaledArray
        }
    
}