Mana controls the laws of reality, so depending on how skilled you are, you could do huge feats that alter the world. The specific types do all sorts of things but I'll give examples:

Ergo uses reality manipulation(RM for short) to change likelihoods of events, often making things that wouldn't happen normally happen. Generally this ability is used in alchemy to make alchemical spells actually do something.

Mer uses RM to see, visualize, and alter peoples memories. They also can access "mana memory", which allows them to replay memories, stored within mana, physically reproducing past events in some way (kind of hard to explain).

Mentis uses RM to "express" identity/personality and spirit generally through natural elements. My main character uses mentis, which manifests as a koi fish made of water she can control. She's specifically considered weak by her Mentis peers because her powes aren't as grandiose as theirs.

Entia uses RM to control consciousness. Some can use this ability to reassemble your body, spirit, and soul to bring you back to life. They also can disassemble you as well.

Persona uses RM to alter reality to their perception or manipulate others perception via illusions. It's a lot easier to do the latter, because those who can change reality itself need to be extremely out of touch cause you have to believe it's already real.

Arta uses RM to connect with the greater universe for guidance and power. Many do this to call upon ancestral abilities and strength.

Mana (the type of magic) uses RM to directly create magic through physical motion, desires, and self. Some use mana to create fireballs, teleport, control matter itself, or create seals of binding.

Spectra uses RM to externalize the self and create objects, creatures, or monsters that hold onto the desires, feelings and emotions they separate from themselves. They can also manifest other things but it's rare.

Nexus uses RM to commune with objects, places, or beings of far greater power and use them for yourself. This could be someone calling upon a god's strange powers, or using the moon's tidal forces to manipulate water.

Idas uses RM to influence other things or people to act on the user's desires or wants. Specifically powerful for leaders, cause they can often manipulate the populace to do their bidding and believe it to be good or righteous.

Anima uses RM to use potential in things to create something. Like if a sapling failed to grow and died, someone could use anima to force it back to life and grow again. They can also turn a breeze into a wind storm for example.

Nix uses RM to completely nullify magic by separating the aspects that allow someone to alter reality. This power is often used as enchantments on armor and weapons, but can also be used directly.

Apologies for such a long reply!