I just went from a 2016 Tahoe to a 2021 Yukon XL. I'm also a fam of 5 with 16, 13, and 9, plus a dog. Just buy the XL. Don't look back, don't question or worry about it, just buy it. With or without the captain chairs, although we do like our kids separated and easy access to the back.
Every time we road tripped the Tahoe I ended up frustrated, pissed, swearing, and sweaty as I played tetris loading all our stuff in the cramped storage of our Tahoe.
I loved the Tahoe but with captains chairs and 3 kids that 3rd row is always going to be up... our poor 3rd child usually ended up in a cave of luggage buried underneath our stuff shoe horned into the tiny spot in the back of the Tahoe.
Now we no longer have to worry and couldn't be happier. So much more space and leg room as well in this new model, but I'd still opt for the XL or suburban. The cost difference is minimal, the fuel economy is about the same, and nobody I've ever come across has ever said they wish they had more space.
Oh and one more thing, get the powered seat downs if you can find it. I test drove a suburban that was all manual and climbing into the back everytime to adjust seats would get old. Much easier to just hit the fold down buttons.
Good luck and hope you find one.