Once upon a time, what would become
 Apex Legends was going to be a sequel to 
Titanfall 2. The latter was Respawn's traditional multiplayer/campaign game in which the player could wallrun and take control of a hulking mech known as a Titan. It therefore comes as no surprise then that Respawn Entertainment were apparently considering adding Titans to 
Apex Legends.
They aren't anymore, however. Drew McCoy, the battle royale game's executive producer, recently did an interview with 
Game Informer in which he revealed that Respawn have officially given up on trying to implement Titans into 
Apex Legends.
This is because taking control of the Titan is meant to imbue the player with a sense of power. However, that feeling vanishes once the Titan has been fine-tuned to a battle royale setting. According to McCoy, they've simply figured out that a Titan isn't the best fit for a battle royale.
"We prototyped it for like nine months during development, and we couldn't get it to work well. Titans were created back in the day as a power item. As a sense of I am now a badass, don't mess with me. That fantasy fulfillment is destroyed immediately in battle royale once you've balanced them to a point where they don't ruin battle royale."
"We could never pull enough levers – how you get it, how strong it is, how fast it is, how big it is, what kind of weapons it has, when do you have it – all that kind of stuff. So I think for now, titans are just not a thing. We're no longer considering it."