How did the 14th amendment increased federal power?

Because of its vague and sweeping language, the 14th Amendment gave the courts great latitude in deciding what is due process and what is equal protection under the law. For example, during the Lochner Era, the Supreme Court believed that the private right of contract was protected by the due process clause. That view of the due process clause has since been discarded. Instead, the 14th Amendment was used to incorporate the Bill of Rights, which meant that states could no longer abridge freedom of speech, religion, procedural due process rights in the 5th Amendment, etc. At this point, the only amendment that has not been incorporated is the 2nd