Heard first appeared as Mera in Zack Snyder's Justice League, before moving on to a more prominent role in James Wan's solo feature, Aquaman.
Starring Jason Momoa as the titular character, as well as Patrick Wilson, Dolph Lundgren, Willem Dafoe, and Nicole Kidman, Heard was featured prominently in Aquaman, almost as a co-lead.
With Aquaman and the Lost Kingdom already delayed into 2023 anything could happen in terms of how much or how little (or at all) Mera appears in the final cut.