It looks very plausible that stretching before you exercise doesn’t do much for you. Multiple older surveys suggested this.
Annoyingly, the studies linked in the previous paragraph are 2 decades old, and somehow I can’t find a large, well controlled, trial.
It is both. Stretching is a kind process that prepares both your mind and your body for the work is coming ahead. It is absolutely necessary to get your body to produce the maximum output. It’s like having a small cup of tea before you force your heart rate to 190 (short of a heart attack,) Someone else mentioned , you have to warm up, then stretch. Then workout, then stretch as a cooldowm to achieve fficiency.