If you cannot install software and specifically need a "no-install" or web-based solution:

: You can quickly resize via the "Send to mail recipient" trick in File Explorer to generate smaller versions of multiple photos instantly. Download - Fotosizer

: Open the downloaded file to begin the 3-step setup process: selecting photos, choosing your resize settings, and clicking start. Why the "Solid Story" Matters

If you are looking to resize images specifically for social media like an Instagram Story, the professional version includes features to expand or pad images to specific aspect ratios (like 9:16) so you don't lose any part of your photo. Alternative Resizing Options

: Click the "Download Now" link. If your browser displays a security warning (common with new releases), select "Keep" or "More Info" -> "Run anyway".