Stride length is a by product of other things happening correctly.
I don’t buy the “one size fits all” model of a stride length being a certain distance or a certain percentage of ones height.
If you want to get more flexible in the lower half (hamstrings, quads, calfs, lower back, glutes act) I would start with foam rolling. It is not comfortable but it a great way to break down some stiff tissue. Especially pre and post workout.
Being able to really stabalize on a strong, firm landing leg should be a precursor to worrying about stride length. Focusing on getting a big stride only to have an unstable, weak leg to land on, well, extra stride won’t do you much good.
Get the gluts active, foam roll the legs, doing a good active warm up pre workout or throwing should help too. Get strong. Legs, gluts, lower back and core…when I say core I don’t mean beach body, six pack abs nonsense…I mean rotational strength and a core that can stabilize the body. Addressing these things should help you to increase stride without forcing it on its own in a vacuum.
Watching your mechanics in the other thread the front leg never gets firm. You land with your knee slightly bent and your leg never straightens, you fall off to the side instead. So, the momentum you have built up with some good things in your mechanics is never fully toward the target.