There's an option in the project settings. With this option, all newly created keys in the reference language are automatically translated into the target languages using machine translation or generative AIs. Existing keys are not automatically translated, but you can also use machine translation in the bulk actions to accomplish this.
You can enable it by navigating to your project settings page, in the "EDITOR, TM/MT, ORDERING" tab and enable the "Enable the automatic translation Workflow" toggle button in the "Cat settings" card.
The whole automatic translation happens in the backend, this means you'll see the translated result after you've saved the new keys in reference language.
The automatic translation can also be triggered via the API, but a particularly powerful workflow is to combine it with i18next's saveMissing feature. This allows your running application to automatically detect and push new keys directly to Locize, where they can be instantly translated by AI.