The Leylines are the branches of Yggdrasil, the tree which all magic comes from. Yggdrasil's branches not only hold all celestial bodies in the sky in their orbits (which we can affirm by the different points in the series where magic is drawn down from the stars and the planets), but it's power is enough to warp space and dimensions to create pocket worlds via quantum superposition, which can only be reached via the leylines. It can even do this when Yggdrasil is in a near death-like state from being starved of belief energy (believing in magi fuels magic). In certain places, the ley lines lead back through time as well as space.
At the end of the series, Akko and Diana absorb enough belief energy to resurrect Yggdrasil and use it as a projectile to return magic to the world. It's only a temporary boost and done with prep and help for Akko and Diana but still. Woodward is also so old and powerful that she's merging with Yggdrasil, and can see the past, present and future, and likely even different futures (it's debatable that she can alter timelines, but I've yet to 100% confirm if she can do this or not).
Chariot also scarred the Moon, mass scattering a country-sized mass of it at thousands of kilometers a second with the belief energy of only a few dozen people (I calced this in the large planet level range, and as per above, belief energy isn't linear in growth). The Noir Fuel Spirit Rod has way more emotional energy than Chariot did when she scarred the Moon (it had the emotional energy of a whole town/city), and was able to nullify the leylines (at least in a certain area) across different dimensions so the only magic that worked had self contained sources (Shiny Rod, magitronixs, the shooting star), and continued absorbing energy from across dimensions. Croix was able to damage it, but it just regenerated. Akko destroyed it in two hits with the Shiny Rod.
The game has the Horologium Chamber causing a timeloop which causes even distant constellations to increase in luminousity. The Time Demon is powerful enough to break this loop. Molly McIntyre was cursed 200 years ago after she became the Ghost Witch, and her power was split behind the 7 doors of the Chamber of Time (even the aspects of her power was enough to cause natural disasters). The game also has artifacts you can wield like the Calamity Rod which has enough power to destroy the world, the Stardust Rod which can control the stars in the sky, the Chaos Wand which increases the power of the wielder endlessly, Judgement Rod which was bestowed by the gods to meet out their judgement, the Fate Wand which can twist Fate itself.
As for speed, Alcor is MFTL,crossing from beyond the galaxy and space-time in seconds, and the power of the stars is called upon/returned at MFTL speeds. Chariot scarring the Moon happened at sub-light speeds.
In terms of hax, there's shapeshifting, transmutation, magic absorbsion, invisibility, dimension hopping (several spells could work across dimensions too, and Croix hacked all the TVs & computers in the world from another dimension), time manipulation (though under most circumstances this only works on a small scale and on inanimate objects, while the Horologium Chamber and the Time Demon can manipulate it on a grand scale; certain artifacts also allow you to change your past), regeneration, control over all four elements (with gravity manipulation falling under earth), soul fuck, intangibility, entering someone elses mind (which ambiguously risks flooding into the real world under certain circumstances), mindfuck, memory manipulation, protective barriers and more.
Even prior to properly learning any magic Akko has city to small island durability (this would also scale to the other seven main witches).
I will post citations for all of this if need be.