I am using a Logitech K250 keyboard on my MacBook Pro. I have already switched the cmd and opt keys in system preferences, but I would also like to remap the function key to option to make it more consistent with the default Mac keyboard. How can I do this? Thank you for your help.
It is possible to do with the Karabiner-Elements app.
As you have completed the installation, head to the app. In the very first tab choose the input device you wish to make a key remap for, then add a new item and define the initial key and target key (they are in the top section of the drop down).
This is it, no need to reboot. It effects immediately.