Is there a stretching only routine for length?

Is there any stretching only routine that work well for gaining length?

Yep. It’s just doing the stretches and not the other parts. However, low-erect jelqing is also recommended for length. Typically speaking, the newbie routine is going to produce length much more easily than girth.

Should It be the regular up, down, left, right and straight out stretches or other ones and how long for each?

That’s the basic idea. Follow the newbie routine. Work your way up. Read the forum.

There’s also the "piss pull," where you just stretch it for 30 sec or so every time you pee, and the "fowfer," where you pull it under your butt and sit on.

Tricks And Tips For Manual Stretching