Copying a folder to an external drive with no permissions


We are finally retiring my wife’s mid-2011 iMac, and for some reason we have always had some weird issues with permissions on this computer and specifically her picture files. While I have copied them to an external drive and they appear to be opening fine by everyone on other computers, I want to copy them one last time and ensure when I do it that everyone has permission to read and write to the files — in other words, remove whatever permission data is currently on the pictures. I vaguely recall reading before that there is a terminal command to do that, but I can’t remember it. Can anyone give me an idea?

While there are Terminal commands, you can do that in Finder.
On the drive or folder, Right-click, Get Info.
At the bottom is Sharing & Permissions
Click the lock so you can make changes
Change everyone to Read & Write
Click the little cog at the bottom, and click Apply to enclosed items…
You’ll be asked if you’re sure, and you can click Ok if you are.