No. Not quite.
Download cpu-z. That'll tell you what ram is in your Lenovo Legion. It'll give you size and amount of ram, speeds, voltages etc. That's what must be the same. So if it's DDR4 1.5v 2133MHz, and there's only 1 stick of 8Gb (there'll only be 1 option, and be listed as single channel, if there's 2 options and listed as dual channel you have 2x4Gb) then you can get 1x8Gb. If it's 2x4GB then you need another 2x4Gb, if the mobo has 4 slots. If it's a 2slot mobo and already has 2sticks, youll need to buy all new ram. You'll need to match the specs, brand is nice but not any different.
And hope it works, there's no guarantee it will.