Yes, eat more and workout harder.

My dad is your same height. When he was 53 he decided to push himself to get a 315lb bench. Just added in whole milk and pb&Js to his diet along with his typical meals. He grew like a weed. Benched 315lb like it was nothing at 53 at 6'7 245lbs. Now of course 315 is warm up weight on the misc, but this was years after not working out at all.

Just start pushing things. Get raw whole milk if you can and add that in. Start by adding 1 thing extra to your diet, then each week or two add a little more to that. So keep eating what you are, then add in like 1 pb&J or shake at night. Do that for a week or two, then when you start to acclimate to that, make it 1 glass of whole milk and a pb&J. Or if you want a cleaner approach use whole foods like oatmeal and eggs, etc.

Tons of ways to gain weight. It is difficult because I struggle with it. Don't have a huge appetite naturally. But I'm only 6'2 and not 6'7 so I can't really say much

Also look up Tom Haviland. He's 6'8. He's on the sauce, but here's a video giving you some idea of how to get calories in. This was years ago, but he now is like 365lbs and eats 11k calories a day.

realistically a good physique i think i have a serious chance of getting (both in terms of mass + leanness) is deontay wilder, ideally though in a parallel universe i'd have anthony joshua's physique lol without enhancements i'm not sure that would be possible, i'll find out in the upcoming years but im not seriously holding on to that lol

i've grown well the first 2-3 years of lifting