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.
im incredibly inflexible for splits and such with the legs but have always been able to folkd up my knees and have my butt on the floor (ok not as much at this age). I can grab my elbo behind my back and I can do the jujitsu wrist stretching excersises to a more extreme level than most others in class. Its like im flexible at the tips but not at all at the core.