Yes you can depending on the scope. First use neutral (which is the transformer center tap) and using a simple dual channel scope measure each side of the transformer. You will see two sine waves 180 degrees apart. So actually if I add the two channels, which most scopes allow I will see a flat line since algebraically adding two channels of the same amplitude which are 180 degrees apart and of the same amplitude will equal zero. However, if using my scope I invert channel two I will see the sum of both wave forms.You can't measure voltage PHASE TO PHASE on a scope like that.
This is also easily done using a scope and differential probes but the method I just mentioned works fine. Again this will be a matter of the scope you are using and the features. My example is based on an old Tektronix 2235 100 MHz analog old scope so nothing new.It is just a matter of manipulating the channels.
Ron