I added sprites from Kenney assets and tried to scale them but the detail disappeared as I increased the size. Do I have to do this outside the engine or can it scale with the resolution improved?
If you scale up a low resolution image it will not improve in quality. You can either scale up and make each pixel larger (ie good for retro 8-bit graphics) or you can scale up and do an interpolation of sorts between pixels to try and smooth things out.
Can you maybe share the image you are trying to scale in original resolution, plus a screenshot of what it looks like when you’ve scaled it?