You really need to get the Hollow Knight: Silksong double jump ability if you want to search every path that the game has to offer. Throughout your journey, you'll see some ledges that you can't quite reach, which is pretty frustrating, but that's where the elusive double jump skill comes in.
Who knows, perhaps acquiring the double jump can even help you to overcome some of the Hollow Knight: Silksong bosses, particularly those who appear later in the game.
What is Hollow Knight: Silksong's double jump?
If you don't know what a double jump is, I have to question whether or not you should be playing Hollow Knight: Silksong, just because it's a staple move that appears in many games, especially platformers, and if you're not familiar with basic platforming mechanics, you're diving in at the deep end with Silksong. To unlock double jump, you need to find the Faydown Cloak, though that's easier said than done.
How do I unlock Hollow Knight: Silksong's double jump?
Let's get this out of the way: you need to get quite far into the game before you can reach the Faydown Cloak. There are also a couple of abilities you need first, one of which is Clawline, which you get in the Underworks, more specifically, in The Cauldron. Other skills you need to have include dash, wall jump, glide, and harpoon.
Once you have the abilities you need, it's time to go to The Slab, but it's not an area you simply walk into, as you need to head to the top-right section of the Deep Docks and let the Wardenfly catch you; this then leads to Hornet's imprisonment in The Slab, where she needs to do her best Metal Gear Solid 2 Raiden impression, as all of her gear, including her red cloak, needs recovering.
After you get your stuff back, you need to go out of the West exit in The Slab, which leads you into the Mount Fay region, and it's at the peak of this mountain that you find the Faydown Cloak. Now you need to prepare for an arduous climb that requires you to use all of the aforementioned abilities and at speed, as the treacherous conditions cause you to lose health as you ascend. One wrong move and it's back to the bottom with you.
At the top, you can claim your prize and rest easy knowing that you have one of the most helpful abilities in the game due to how versatile it is when you use it with other skills.