How the 200 KB target works
Instead of guessing a quality setting, the tool tries different compression levels and keeps the best-looking version that is still under 200 KB. If a very large photo is still too big even at the lowest quality, it is scaled down a little as well, so the result meets the limit.
200 KB is enough for a clear, full-screen photo. Most people cannot tell a well-compressed 200 KB JPG from the original on a phone or laptop screen.
When to choose a different size
If a form says 'maximum 100 KB' or '50 KB', use those tools instead, because they target the smaller limit directly. For printing or professional work, keep files larger, such as 500 KB or more, so fine detail survives.
PNG files are saved as JPG in target mode, because PNG cannot be compressed to an exact size. If you need transparency, use the WebP format or keep the PNG and resize it instead.