> What are the chances that it will charge my MacBook Pro 16 inch that does support “standard” USB C?
Most likely yes, unless it's a non-compliant cable in the first place, and possibly at a reduced speed (60W max).
>Will that “standard” USB C cable that comes with my Beats Flex headphones charge my iPhone 12 Pro Max? My Anker battery?
Ignoring that iPhones don't have USB C, yes to both at the fastest charge rate available.
Only times where you have to worry about a cable with USB-C when charging is if charging power exceeds 60W or the cable is optical. Above 60W you need marked cables, some go up to 100W, and some (will, not seen in the wild yet) go up to 240W. There are plans to deprecate the 100W tier as well.
Most likely yes, unless it's a non-compliant cable in the first place, and possibly at a reduced speed (60W max).
>Will that “standard” USB C cable that comes with my Beats Flex headphones charge my iPhone 12 Pro Max? My Anker battery?
Ignoring that iPhones don't have USB C, yes to both at the fastest charge rate available.
Only times where you have to worry about a cable with USB-C when charging is if charging power exceeds 60W or the cable is optical. Above 60W you need marked cables, some go up to 100W, and some (will, not seen in the wild yet) go up to 240W. There are plans to deprecate the 100W tier as well.