The Alexa Skills Kit provides this type of control with Speech Synthesis Markup Language (SSML) support. SSML is a markup language that provides a standard way to mark up text for the generation of synthetic speech. The Alexa Skills Kit supports a subset of the tags defined in the SSML specification.

https://developer.amazon.com/en-US/docs/alexa/custom-skills/speech-synthesis-markup-language-ssml-reference.html