A few years ago there were suggestions on apps to resize pics more suitable for posting.
My search didn't show what I was hoping for i.e. app names.
Any suggestions for Windows 10 would be appreciated.

Thanks in advance.

Microsoft Paint still exists in Windows 10, it just isn't easy to find in the menu system.

Right-click your image (jpg, usually), select "edit", and McPaint comes up.

Inside there, "Resize" shows up in the "Image" group. It does as-advertised. I generally use values of 25/40/50 % to reduce photos taken with phone, tablet, Nikon.

You can toy around with resizing, too. If you enter a number and don't like the end result size, Control-Z to undo your resize. This gives you room to fuddle with it to find the right number.

(ETA) I pretty much have stuck with McPaint for simple jobs. It does basic cropping as well if you don't want to post "full frame" shots.

There is also a free editor, replacing standart Paint.
Works very well.
https://www.getpaint.net/index.html