Long time lurker who just made an account here. There is
a lot of bullshit out there that you have to sift through to find actual practical methods, but those methods do exist. This community is a good place to start. Don't hesitate to ask lots of questions no matter how dumb they may seem.
A length gain of 1-1.5 inches over time is not unreasonable with manual stretching. There are forums here dedicated to PE you can check out plus other sites like Thunders and AJelqForYou on Reddit.
For
Girth, lots of people have success stories with injections.
Hyaluronic Acid is the safest to put in your body, but temporary and does not give the biggest gains.
PMMA is permanent and gives great gains in
Girth, some have gone 1.5" or even 2" in
Girth bigger. There are many reputable clinics with plenty of success stories on here.
As for penuma, as far as I know, there is no known patient confirmed to have kept his implant. It's only nightmare story after nightmare story. Everyone has it removed with varying degrees of complications ranging from (most common), permanently shortened length to loss of sensation, weaker erections, etc.
I think you can definitely achieve a 5.5x4.5-5 with the right methods. Good luck with your PE journey.