assigning role for different users in Django Rest Framework

I have used AbstractUser defined in Django for user model and have a UserProfile model which is one to one relation with the User. Now I have to implement a role-based authorization for the CRM project that I am writing.

What will be the best approach to assign a role? Should I use add fields inside the user model or inside the UserProfile model? Or I should use the already defined superuser,is_staff or active status inside User model.

My models:

class CustomUserManager(BaseUserManager):
    """
    Custom user model manager where email is the unique identifiers
    for authentication instead of usernames.
    """
    def create_user(self,first_name,last_name,email, password, **extra_fields):
        """
        Create and save a User with the given email and password.
        """
        if not email:
            raise ValueError("The email must be set")
        first_name = first_name.capitalize()
        last_name = last_name.capitalize()
        email = self.normalize_email(email)

        user = self.model(
            first_name=first_name, last_name=last_name, email=email, **extra_fields
        )
        #user = self.model(email=self.normalize_email(email), **extra_fields)
        user.set_password(password)
        user.save(using=self.db)
        return user

    def create_superuser(self, first_name,last_name,email, password, **extra_fields):
        """
        Create and save a SuperUser with the given email and password.
        """
        extra_fields.setdefault('is_staff', True)
        extra_fields.setdefault('is_superuser', True)
        extra_fields.setdefault('is_active', True)

        if extra_fields.get('is_staff') is not True:
            raise ValueError(_('Superuser must have is_staff=True.'))
        if extra_fields.get('is_superuser') is not True:
            raise ValueError(_('Superuser must have is_superuser=True.'))
        return self.create_user(first_name,last_name,email, password, **extra_fields)


class CustomUser(AbstractUser):
    username = None
    email = models.EmailField(unique=True)
    first_name = models.CharField(max_length=255)
    last_name = models.CharField(max_length=255)
    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = []

    objects = CustomUserManager()

    def __str__(self):
        return self.email


ROLE = (('admin','ADMIN'),('manager','MANAGER'),('staff','STAFF'))

class UserProfile(models.Model):
    user = models.OneToOneField(CustomUser, on_delete=models.CASCADE,related_name='profile')  # Delete profile when user is deleted
    image = models.ImageField(default='default.jpg',blank=True,null=True)
    address = models.CharField(max_length=150,blank=True)
    mobile = models.CharField(max_length=15,blank=True)
    job_position = models.CharField(max_length=25, blank=True)
    role = models.CharField(max_length=15,choices=ROLE,default='staff')

    def __str__(self):
        return f'{self.user.username} Profile'  # show how we want it to be displayed

For now, I have added the roles inside the profile model. But what I think is, if I am dealing with user inside every api, the field role should be defined inside the User model as it makes it easier.