autoasignarse

To self-appoint or assign oneself something — a task, a role, a privilege — often with a critical edge suggesting the person gave themselves something without proper authority: se autoasignó el cargo de director.

• Se autoasignó el papel de líder del proyecto. — He appointed himself the leader of the project.
• El empleado se autoasignó las tareas más sencillas. — The employee assigned himself the easiest tasks.
• El funcionario se autoasignó un aumento de sueldo, lo que generó polémica. — The official awarded himself a pay raise, which caused controversy.

Missing the mildly critical tone the word usually carries — autoasignarse often implies overreach or self-serving behavior, not a neutral assignment made by someone else.