If that’s what you need this plugin might be for you. I haven’t used it but it seems like it’d do the trick.
Also, the use isn’t just for saving time, which by the way can become substantial since checking how your UI looks in different aspect ratios is a slow process and something you end up doing a lot. The other purpose is to allow you to create UI while simultaneously seeing how it will look on different devices. If you create the UI in desktop mode it will look best for pc players. At the end, when you preview the UI for phones and tablets, you’ll probably just fix the glaring issues. You’re not going to completely redesign it. However, if you see a preview as you’re creating it the UI you’ll be able to choose the design that works best across all devices.