A script to batch resize images through the Windows command line (cmd)
Get a copy of ImageMagick : https://www.imagemagick.org/script/download.php#windows and install it for using magick.exe include the excecutable in your PATH in case the script doesn't work
Do magick.exe mogrify -resize AxB -path / input.ext output.ext where (A, B) is the target resolution and input output for batch conversion can be any image format *.png *.jpg etc.
Alternatively get Gimp use it : https://www.gimp.org/downloads/