Ideally, you'd get a bike fit before investing in a new bicycle; if you don't have a local fitter, possibly an online tool such as MyVeloFit is sufficient to give you at least ballpark numbers.

Lacking a fit, see what some of the major manufacturers recommend. Canyon for example suggests size XL for their Endurance CF 7 frame for someone your height (see attachment). Consulting the geometry chart, this frame (in size XL) has a 637mm stack and 405mm reach.

It's similar for other manufacturers: Specialized Roubaix size 61 - 630mm stack, 397mm reach; Giant Defy size XL - 615mm stack, 402mm reach.

To answer your first question, definitely look for a 610+mm stack frame (unless you have specific fit numbers). To partially answer your second question, the AliExpress experience is very much the opposite of what you are looking for. It offers gazillions of individual components rather than fully-assembled bicycles. It targets the meaty section of the bell curve rather than the very tall and the very short. It caters to the race/competition crowd much more so than to the endurance folks.

If you want to continue down the Chinese route, you may have more luck with a gravel bike since their geometry is generally more akin to an endurance bike. I'd take a look at TanTan/Seraph; this isn't an endorsement as such but maybe it serves as a reference point against which to compare other vendors.

Example 1,  based on TanTan GR206 frame: https://tantanbikes.com/13-Speed-Full-Bike-Disc-Gravel-Bike-GR206-Wheeltop-Gex-Groupset-Single-Speed-Di2-Complete-Bicycle-Aluminum-Wheelset-700X40C-Tire-p6885384.html
Size L - 620mm stack but also long reach (422mm - you may want to specify a shorter stem)

Example 2,  based on TanTan GR208 frame: https://tantanbikes.com/GR208-Disc-Gravel-Complete-Bike-WheelTop-EDS-113S-Groupset-p6908001.html
Size XL - 607mm stack (on the short end)

Caveat emptor: to (hopefully) find a configuration you like, you need to carefully sift through their full catalog and hunt for the groupset/wheels/color you want, or maybe talk to them directly.
https://tantanbikes.com/Full-Bike-c202763/

Do you have Decathlon in your region? Their Van Rysel bikes are really high value and you’ll at least have some basic after sales support. Buying a complete bike from China with zero experience setting up a bike isn’t impossible, but it’s a poor choice.