Is there really a specific age that’s right?
French President Emmanuel Macrons wife was his school teacher. Some of her children are older than him.
If you marry someone around your age you’ll probably understand each other better, but there may be less respect (maybe, maybe not). You need to see yourselves as twins perhaps.
If you marry someone much younger than you, probably there’ll be respect for you but the person may not understand some of the the things you understand or feel at your level. You’ll often need to be patient.
If you marry someone much older than you, then my advice is: be humble so it can work because that person has seen some things you haven’t. And be understanding.
All in all, it depends on the couple themselves: the most important question to me is, do the couple love (and understand) themselves? If they do, they may be able to withstand a lot of things…