I can't find the end portal

The conventional method for finding an End Portal is to use Eyes of Ender (Combine Blaze Powder with an Ender Pearl). When used, they will float up in the direction of the closest End Portal, then after a few seconds, either fall back down, or break.

Once you get within a certain range of an End Portal, the Eyes of Ender will then float down toward the ground. This is where you can start digging, as the Eye of Ender will (generally) indicate you are directly above the portal.

As for using the "x-ray glitch" and "digging out the entire area", an End Portal is a rare occurrence. If you managed to find one near your spawn (say, within 64 chunks) you'd be incredibly lucky.

Remember not all strong holds have portals, and depending of the seed these structures might be thousands of blocks apart.

Might want to try another Seed: -1075018877 go/teleport to coordinates: -863, 62, 1115