Choose the format for the actual image
Photos are usually good candidates for JPEG or WebP. Start with PNG or WebP for sharp screenshots, icons and transparent graphics. JPEG cannot retain transparency, so inspect the background before exporting.
Keep the original and compare settings on the same image. Record source and output dimensions, format and bytes. Comparing file sizes alone can confuse a reduction in pixels with an advantage of a format.
Quality and dimensions solve different problems
Quality mainly affects JPEG/WebP encoding; PNG does not respond in the same way. A maximum width reduces pixels and often helps large photos, but removes detail. Do not reduce quality indefinitely just to satisfy a size limit.
A 2400×1600 photo limited to 1200 pixels wide should become 1200×800 when its ratio is preserved. That is one quarter of the pixels, but not necessarily one quarter of the file bytes.
Why 200 KB is an approximate target
Target mode tries to approach the selected size. Detail, format, transparency and the encoder affect the result. An already small image may not shrink much, and re-encoding can even enlarge it.
Try 200 KB and inspect the actual output. If a receiving service rejects it, lower dimensions or quality gradually. Check how that service defines KB and measures its limit rather than relying only on a rounded display.
Four checks before downloading
Zoom into text, edges, gradients and faces; check transparency and dimensions; compare actual bytes; then open the downloaded file. If the result is larger or worse, keep the original and change settings.
Inspect every file in a batch ZIP. Compression is not automatic redaction: visible names, addresses and other private details may remain and need separate treatment.