Question about Shadowlands

I havent played WoW since legion and I had to start an alt character because of how lost I felt when I logged back in for the first time to my main. Whats the best way to level up this alt and catch up to where the expansions are at?

On this alt, just level in Legion content to 48 at which point you can go to Shadow Lands.

Once you get any character to 50, you can use chromie time to level any character from 10-50 in any expansion. Mobs and dropped gear will scale to your level.
WoD, particularly Gorgorond, is favored by many looking to level quickly as XP is a bit higher there when compared to other zones.

My alt is actually a Blood Elf Death Knight, I just changed it on the forums, level up through the same way?