Staff augmentation
Staff augmentation is adding individual external engineers to your own team. They join your standups, take tickets from your board and are managed by your tech lead, so you rent skill while keeping full control of how the work is run.
Staff augmentation is the right tool when you have a clear plan and a specific gap: a React engineer here, an AI specialist there. You are renting skill and keeping the steering wheel.
The trade-off is management load. Because the augmented engineers are managed by your side, the onboarding, code review and unblocking stay your job. With one or two people that is fine. As the number grows it quietly becomes a second job for whoever owns it, which is the point at which a dedicated development team often makes more sense.