Turn out comes from the hips, not the ankles or knees. Your boots have literally nothing to do with your turnout - aside from your mount alignment being proper to allow you to do things like Ina Bauers and Spread Eagles, Spin, etc.
If you want to help your skater's turn out, enroll them in ballet classes. That will teach them to turn out safely, because a lot of people force turnout from the wrong places and this leads to overuse injuries from the bad mechanics.
Also, off-ice, because it takes strength to hold turn-out and if those muscles aren't developed, they will just overuse and wear them out (e.g. injure themselves).
The cut of the boot can help with toe-point, however.
If the skater pronates and tends to need blade adjustments, this is one reason to avoid the RF line and go with the Royal line, which still uses leather soles. The RF line has moved to synthetic soles, and those holes are pretty much impossible to plug properly. When adjusting a mount, sometimes the mounting holes need to be moved, which requires plugging the prior hole and drilling a new hold next to it.