I used to have an '05 Sienna XLE AWD and while I loved the vehicle, I don't think I'd want to really try to tow anything with it. It's wonderful for moving people around but adding tongue weight to your cargo load as well as skis and clothing for five people (assuming the dog doesn't ski

) and I bet you'll be overloaded.
Since the Sienna engineers put in a dial to lower/ raise the headlight height, I figured they weren't counting on the rear suspension to keep level when fully loaded.

While we sold the Sienna a few years ago (amazingly got above blue book after 11 years because of all the features it had!), we recently bought a Sequoia for towing our CL 14DBS. We had a '17 Jeep Cherokee that was -just- capable of towing the 14DBS but between problems the Jeep started having and not enough towing comfort margin, we decided to change. I found the Sequoia to be happily quite a bit like the Sienna inside! Window shades in the rear, dash config, how the seats work, the plethora of cup holders...

If you do look for a Sequoia, I heartily recommend the Platinum trim level as it has rear air suspension that can help level out tongue weight. Many of the towing reviews I read about the Sequoia complained about the rear sag but they were all testing the SR5 or TRD trim level which do not have the rear air suspension. The reviews also complained about how "old tech" and "out of date" the Sequoia is, but the used 2018 we bought has all the safety things like our Jeep did (blind spot, lane departure, etc) and having a tried-and-true engine and transmission were a huge selling point to me.
For you with 3 kids, it may be a drawback that the Platinum only has captains chairs with console in the second row, so your third will always have to sit in the third row. But, since I grew up sitting in the middle of a bench seat in a station wagon, I would've far preferred a third row so maybe that would work out for you.
Before I tout the Sequoia too highly, I guess I should add that you should closely look at its cargo capacity and wheelbase to compare against your kids' future growth and possible trailer upsize. Other possibilities for you might be a Ford Expedition Max, I think it's called, with a longer wheelbase or something specifically designed for towing. Or the old standby Chevy Suburban 3/4 ton. Both of these were too long to fit in our garage, along with every pickup I could find, so I didn't look at these too closely.
whew, maybe TMI but hope this helps
cheers