Sadly, it isn't possible to have control over this! There are so many influences that are beyond our control as Mums; pelvic shape for example. Every Mum is unique in that regard and every baby is unique too. However, the late Jean Sutton, and many other midwives, feel that mothers can take some actions to increase the chances of their babies being in a helpful position for birth. You can read a whole lot more about what became Jean Sutton's life's work on Optimal Foetal Positioning (OFP) here.
The short version is to keep knees below hips from 36 weeks on. This tips the pelvis forward and may encourage the baby to lie with his or her head and back toward Mum's front; rather than lying with his or her head and back towards Mum's back, a position that is associated with longer labours.
Mums can use cushions under their bottom; relax on their left side on a sofa of an evening (rather than leaning back); adjust car seats and/or office chairs; and consider sitting on an anti-burst gym or birth ball that is large enough to keep
knees below hips but still have feet flat on the floor so you don't roll off! All fours position and any leaning forward position may also help, but are not possible to use all the time.
I tried Optimal Foetal Positioning (OFP) with all 3 of my babies, and they all engaged back-to-back! So it's not a guaranteed thing. There may be anomalies about my unique pelvic shape that mean my babies need to engage back to back and I didn't find that it slowed my labours. So be encouraged! OFP is a simple adjustment to life that may increase the likelihood of a straightforward birth, but it's not the be all and end all.