The users can either warp or drastically distort the fabric of reality through either:
The usage of dimensional phenomena, that is, the conjunction of spatio-temporal distort the physical plane for various effects.
An influence from a dimensional/existential plane, merging the plane to direct the affected area's existential state.
Last but not least, the mere warping of dimensional planes according to the user's whims.
The user's potential is only tied to their creativity, functionality, and methods; this entails a higher versability or comprehensiveness in certain respects, as they can both get a handle of the space-time continuum.
Bill Cipher's (Gravity Falls) source of power is the interdimensional rift, which merged his dimension (the Nightmare Realm, a chaotic intergalactic foam devoid of physical laws) with our world. This allowed him to gain a physical three-dimensional form and manipulate the laws of reality, like ha can transform organic matter, disorient the physical world, and cause a ripple in the space-time continuum. After breaking the Nightmare Realm, Bill's powers grew stronger to the point where he can manipulate reality on a cosmic scale.
After his training at Kamar-Taj by his mentor the ancient one, Doctor Strange (Marvel Cinematic Universe) is able to manipulate Mirror Dimension Magic. he can easily be capable of manipulating a city-wide space within the Mirror Dimension, and was capable of conjuring a construct of the Mirror Dimension in the form of crystalline fractals that acted as a shield, absorbing an energy beam from the Power Stone and was also able to send the fractals at Thanos.
Paradox Prism (Sonic Speed Simulator/Sonic Prime) is a gemstone of cosmic significance that can alter reality itself, shattering it will wiped out reality and creating alternate dimensions within creating the shatterverse. It holds unlimited energy, have different shards abilities, and can manipulate space and time.
Solaris (Sonic the Hedgehog)
Kaguya Ōtsutsuki (Naruto)
The Beyonder (Marvel Comics)
Sorcerers like The Ancient One (Marvel Cinematic Universe) can fold matter, gravity, and the laws of physics in the Mirror Dimension, she can trap opponents in the Mirror Dimension, a parallel reality she controls, and she is also connection to the Dark Dimension that allowed her to warp space in the Mirror Dimension. It was unknown if she could achieve this feat on earth like Kaecilius could, but it was likely that she can be due to her being more powerful than him, and also displayed being able to counter a shockwave from Kaecilius's warping of reality and even repel Kaecilius also by slamming her hand to the ground and summoning a shockwave of her own.
After being performing the ritual to tap and empowered by of the Dark Dimension, Kaecilius (Marvel Cinematic Universe) was able to manipulate space. This allowed him to warp and twist the landscape of the Mirror Dimension, as well as the inside of the New York Sanctum. Also, he could run on walls and ceilings, totally disregarding gravity. He could also use his manipulation of space to conjure Space Shards. In addition, his momentum seemed enhanced to the point where he could easily send someone flying with his attacks, especially while defying gravity. he had gained the ability to manipulate matter outside of the Mirror Dimension at will, which he used to warp reality around him to defeat his enemies, being able to compete against the likes of the skilled, Doctor Strange, and his former mentor, the Ancient One.