Neon, Viper, Reyna, Phoenix, Fade, Gekko, Astra, and Jett are all agents that have passives. The valorant wiki explains what these passives are and why they're considered so. I would suggest giving it a read
Hmm. Most of these passives however require the player to use the ability (fades trail requires eye/ult to be used, viper's require wall/orb). I was kind of referring to passives that could be in play without a character using an ability