Is there any mods available to download where player can use spell and somekind change to monster.
I can't explain it, but like Martin did in last cinematic.
Are there any?

There are some Werewolfe mods out there, but the Werewolf isnt very much taller then a human.

A Giant Thing like the Akatosh Dragon would be a Pain in your behind. Indoors, you would have to fight as a "normal" Version. When you activate the Monster form indoors, you would be stuck right there on the Spot for all eternity, or until the Spell wears of...
You wont be able to see anything, because your Head is several meters above the ceiling of most indoor locations.

It would be a nice showeffect running around as a giant. Outdoors, on a perfectly leveled Ground. Without Trees messing up the Collisions...

I already know werewolf mod, but thanks still.
Is it able to make race wich is BIG, and make a spell where your character changes to this race?
Is there able to make bigger than 2.000? And if idea works, what scripts I should use?
Plz answer.

Essentially no.

Giant monsters like Dagon don't have very much defined for them within game to let them even do simple things like moving. The dragon shown in game is actually an activator, so doesn't even do that much. Now people have taken the dragon model and animated it further, but it is still rather limited as to what it can do.

Even if there were models available to be used, the game does not allow the player to be anything other than an NPC, and this is why several werewolf mods just have the player wearing a sort of fur suit. There are polymorph mods which allow the player to be made invisible, and then have a spawned creature which will move in relation to how the player moves, but those mods require OBSE, and aren't very practical for anything very large due to the fixed player perspective height.