Yeah! So a general step by step guide is as follows:
1) Walk off the side of a block. (if you just stand on the corner without moving, it will not work)
2) Right in the time after you've left the block, but before you start to fall, press dash and jump at the same time (the same frame for best results. Either way, it's VERY precise). Hold jump for maximum height.
If performed correctly, you should "jump" about 3.5 blocks up in the direction you dashed. Speedrunners have named this trick a "superjump".
Here's a more technical explanation if you wanna get into the nitty gritty though:
In this game, there is coyote time, whereby after you leave the ground, you still have a few frames where you can jump. During this time, you are also in the air, allowing you to dash. So there is a period of a few frames after you walk off a block where you can BOTH dash AND jump.
What this allows you to do is interrupt a jump by dashing, then immediately jumping during these few frames. Due to the order of processing events, you can do this jump interruption on the SAME FRAME as when you start the dash. Now normally, dashes should never be "cancelled" by jumping, so the game gets confused and converts some of the dash acceleration to being in the direction of the jump. Thus giving a higher jump.
If you're exceptionally observant, you may notice that if you dash on the first possible frame, you actually have several frames afterwards to jump due to how generous the coyote time is. And this is true! But the delay means you have less instantaneous dash acceleration, and you have a smaller superjump as a result.
Hopefully that helps! ^w^