Looking for features available in Vertica and documentation page.

Are you talking about objects Vertica can "CREATE"? If so, see: https://www.vertica.com/docs/10.0.x/HTML/Content/Authoring/SQLReferenceManual/Statements/CreateStatements.htm

This helps, but looking for feature available Vertica page. I can't say for sure Vertica doesn't have database triggers, synonyms, packages, index for data as objects, until I read the documentation.
Also How'z create any table, alter any table in multiple schemas are supported?

You should start with concepts rather than specific language elements as some database elements are implemented in a Vertica-specific way with sometimes different names; for example, database indexes are called "projections" in Vertica, and projections differ from indexes in that all data in Vertica is stored in a projection, so effectively all data are in column-oriented storage that is sorted and grouped like an index.
Vertica Concepts and Architecture: https://www.vertica.com/docs/10.0.x/HTML/Content/Authoring/ConceptsGuide/Other/ConceptsGuide.htm
All supported SQL language elements, data types, functions, statements are documented at:
https://www.vertica.com/docs/10.0.x/HTML/Content/Authoring/SQLReferenceManual/SQLReferenceManual.htm
Multiple schemas are supported with standard dot notation "schema.table" and the standard SQL statements such as CREATE SCHEMA "schema" and CREATE TABLE "schema.table" are supported.

Thanks for the details.
Please provide the document link for creating table in multiple schemas. What privileges a user needs to create tables on another schema.

It's GRANT CREATE ON SCHEMA my_schema TO that_other_one;
And the link is:
https://www.vertica.com/docs/10.0.x/HTML/Content/Authoring/SQLReferenceManual/Statements/GRANT/GRANTSchema.htm

I would also strongly suggest you go through "Getting Started" and "Vertica Concepts" that you find on the left navigation column, so you can check at your own pace and don't have to wait for someone to pick the thread up

The home link to the Vertica docu is:
https://www.vertica.com/docs/10.0.x/HTML/Content/Home.htm