GI Joe and Cobra aren't locked in the eighties. While several characters may be a bit static in their standard equipment, there's no reason why every GI joe needs to be a machine gunner greenshirt, and every Viper agent a faceless agent. Time and technology march onward. When thinking of new Joe or Cobra OCs, don't be afraid to draw inspiration from more recent sources. While certain ideas, such as a time-displaced skirmish heroine might be a bit much still, there's a wealth of options available from skirmish games like Overwatch, Valorant, and Apex Legends.
Take a look.