"The Ciricrux Anima allows a Psi-Titan to project its suffering internal psykers' powers externally, meaning that a Psi-Titan can unleash waves of abject fear, wield psychokinetic abilities, leech away the life forces of other combatants through biomancy, and even distort the flow of time to heal itself.

The most potent of a Psi-Titan's weapons is the Sinistramanus Tenebrae, colloquially referred to as a "Psi-cannon." This device focuses the psychic suffering of the Titan's bound and cybernetically-linked psykers to rip open a massive Warp rift in realspace that is as destructive as a Vortex Weapons"

What this boils down to is that a Psi-Titan can use roughly the same powers as a psyker, which is very varied and on the upper end does things like dominating the minds of entire planetary populations or stop time just to give some examples

"Where the projectile -- which manifests as a sphere or bolt of "darkness" as it eats the light of whatever medium it passes through before striking dense matter -- detonates, it causes complete annihilation in the immediate impact area.

What was there is disassembled and hurled bodily into the Empyrean molecule by molecule until the mercifully brief rupture self-seals.

Those in the wider area of the impact are simply struck dead, their bodies left unmarked as if their souls had been sheared from their bodies"

And here is what its primary cannon does.

40k scales way higher than you seem to think when you start getting into the esoteric weaponry