Based on what is said in Puranas I just visualize him in my way

Kalki, also called Kalkin, is the prophesied tenth avatar of the Hindu God Vishnu. His birth will be the end of the Kali Yuga, the final of the four eras, in the endless cycle of existence within Hinduism. This will subsequently start a new cycle with Satya Yuga. He is described in the Puranas as the avatar who rejuvenates existence by ending the darkest and destructive period to remove adharma and ushering in the Satya Yug