By default, the S10 doesn't have its display set at maximum resolution. This aims to save a little battery life, but it means you're missing out on some sharpness and some pixels. If you'd rather have the maximum display resolution and don't mind the battery life hit, open up Settings and choose Display, then Screen resolution. The maximum you can go on the S10 is WQHD+, or 3040 by 1440 pixels.
