Tony; welcome to the forum. As you said, you are 5,9 inches measured bone pressed on the side. The guys on this forum usually measure their penis ( bone pressed) on top of the penis, as measuring on one side gives a «false» length. You can, if you wish, ignore what I just wrote and keep measuring on the side - but remember to keep doing it the same way always, to see if you are gaining.
From 5,9 to 8 ? Yes, it is doable, ( for many guys ) but it will take time and work - a lot of it. I am talking about up to 5-10 years to achieve that, if you have a penis that will grow and grow.
Start with 6 months of the neewbie routine ( use the search button), before you start bying equipment like ads ( all day stretcher), extender, pump, hanger and so on. Good luck with the journey, and keep us posted.