I would like to know if it is possibe or avaliable the stackexchange sites database model.
If yes, where could I get it?
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You can get the schema for the data dump and SEDE in this Meta Stack Exchange post.
The architecture of the production database is not available to non-corporate customers (if it's available at all). But, you can grab one of the public domain Stack Exchange clones; their schema is no-doubt similar.