It resizes it from 5760x3840 to 1880x1253, if you lower the quality you can get similar results with any script/program.
https://i.imgur.com/Lz90Zmo.jpg (126kb)
with: convert "original.jpg" -quality 70 -resize 1880x optimized.jpg
https://i.imgur.com/Fj8BUB1.jpg (220kb)
with: convert "original.jpg" -quality 90 -resize 1880x optimized.jpg