Like doing the level in an unintended way (skipping some part) or doing like a wall glitch or something of that sort?

a glitch would be doing something like the wall jump glitch or wall clipping glitch where it is unintended or not required to complete a floor/tower.

theres a block thats too little or too high that can be used to skip something (dont judge)

What he said^^

So doing something like a stair clip that wouldnt affect the run here but breaks other games would be allowed?

After some roblox physics update, there's this high jump glitch going on in some recent glitchless speed runs. I bet it might get patched in the future, too.

highjumping is not a glitch

highjumping is glitching. Its abusing the engine in unintended ways.