yes, i highly recommend using a mixed spectrum for all growing, not just autoflowers. the sun always puts out both spectrums, just more blue than red in spring/early summer and more red than blue during late summer/fall.
Autos should have a shift from mostly blue to mostly red when flowering begins, they just don't have a photoperiod change to trigger it. When you see flowering begin, then shift to bloom nutes and mostly 2700k light.