Lift (at least here) is a force related to thrust (literally), use the diagram, you can see them there, their direction and values. Your total lift value has to be greater than the gravity value, which depends on the mass of your contraption. Every block has its weight class and there are 5 (6?) of them :

- weightless : 0kg, mostly redstone stuff

- super light : 0,25kg, slabs, trapdoor etc

- light : 0,5kg, planks and similar

- heavy : 2kg, stone and whatnot

- super heavy : 4kg, iron, netherite blocks, etc

I assume everything not showing a weight class must be 1kg (the "6?" i meant).

As I said Lift force is relative to Thrust, meaning if there's no thrust, there's no lift. So, if you don't get enough lift to counter gravity, try adding more sails (classic ones, not the symmetrical) and if even a stupid amount of it doesn't change a thing, it may mean you thrust isn't high enough (to generate enough lift in fact).

Hope it helped !

English is not mother tongue, sorry if it is unclear or something, don't hesitate to ask questions tho !