: Aim for a resolution of 1920 x 1080 (1080p) . At this size, a JPEG saved at roughly 80-85% quality usually lands right around the 210 KB mark.
If you were looking for a creative "piece" to fit this limit, here is a concept for a digital art entry often seen in community challenges like the Krita Art Challenge: Community Perspectives on File Sizes (210 KB)
A file size of exactly 210 KB is often a target for high-quality web assets—large enough to maintain crisp detail but small enough to load quickly on most connections. The "Perfect" 210 KB Image : Aim for a resolution of 1920 x 1080 (1080p)
Autodesk Community, Autodesk Forums, Autodesk Forum · 8 months ago Solved: Change lines behind transparent elements into dash The "Perfect" 210 KB Image Autodesk Community, Autodesk
“I've found it has the most useful at-a-glance information out of all the debug screens.” Developer Forum | Roblox · 1 year ago
Since your request is quite brief, I've prepared a "good piece" that fits the specific technical constraint of your subject line: a optimized image for the web.
: Use WebP if you want better quality at that size; it can often deliver a sharper image than JPEG while staying under your 210 KB limit.