How to hoist hot tub out of surrounding deck?
I'd be cautious building something like this with limited woodworking experience. Typical framing like this would have 1/2&quot; bolts and your rough sketch is similar to other stable gantries.
I see this a lot in Florida where people have partially below grade hot tubes and need to raise them for drain and piping replacement. Renting a gantry seems to be the popular way to do this. Some with wheels on the base allow you to move it out of the way to do your work. See picture below. This might save you some time and keep you from having to build one yourself.

I have no business interest in any rental companies.