Camera EXIF (ISO, shutter, lens, GPS) is preserved by default during JFIF → PNG conversion when both formats support metadata. Use the privacy option to strip metadata before download if you want to share images without geolocation.
Default behaviour is 1:1 — your PNG output has the same pixel dimensions as the source JFIF. If you need to resize as part of the conversion, use the /resize-image/ tool after conversion, or chain it with the /image-resize/ utility.
How small can the PNG file get without visible artifacts?