That's a linear BEC and 5v low drop-out regulators are pretty common. Also, a BEC output of 5v on 2s lipo ensures the output won't change near LVC due to dropout.
If you want exact 6v or higher, get a BEC or one of these
and add the appropriate resistors. Just be aware of the dropout.
If the servo accepts 7.4v, just run battery power (2s only) directly to the servo and have the BEC just power the receiver. This would require a bit of wiring, but nothing too complex.