Hi! Lifelong climber (grew up on doing free climbs) and I have some thoughts.

First off, please go to a climbing gym or two and take a beginners class. I can't account for someone being an asshole but I can tell you that older climbers are definitely excited when someone's interested in their thing, like most usually are. With that said, I want to give you a fair warning. My number one concern for someone of your stature would be foot/ankle injuries and pulley injuries (fingers) with rotator cuff being second.

With that said, I completely think you could do bouldering and frankly the fact that you're already a frequent gym goes/weight lifter means you have a, forgive the pun, a leg up on most who are gonna walk in that gym. Take it easy, don't try and do anything absurd, and have a good time. If you're renting shoes from the gym then keep in mind that climbing shoes are a WHOLE thing and finding a pair that work and don't completely murder your feet is a project in and of itself even with average sized feet, your size 16s might be a bit of a secondary project tbh. But spend some time on a wall and see how you feel about it truly after having someone give you some pointers as it's an activity that is closer to 75% technique and 25% strength so knowing some beta (climber speak for "meta" - knowledge of a route/problem) actually goes a long ways.

Edit: Seriously though, the difference between an everyday rental shoe and a shoe that is higher quality and fitted properly to your foot actual does make a tangible difference in how you "feel" and whether you get positive response from the wall/foot connection. Good traction will ensure you can get grip even on the face.

You’ll learn footwork over time. I would absolutely recommend going back a few more times and maybe sign up for a beginners class. I started climbing a few years ago and it has been the best decision I’ve made in a while

The shoes may be the only issue, as few brands even make climbing shoes in those sizes. But I see people of all shapes and sizes at the gym and at the crag, and everyone is there to have fun. It`s a very low-judgment sport, some just like climbing easy stuff, and others like pushing their limits.

yeah rock climbing is really hard for big guys but its still enjoyable. You wont be doing crazy walls but you can have fun at any level