Nested async & await in Web API application

I want to build asynchronous Web API using .NET Core

If I have async Task that's awaiting for a result from the service as below

        [HttpGet("User/")]
        public async Task<IActionResult> GetUser()
        {
            var result = await _service.GetUser();
            return Ok(result);
        }

Now in _service.GetUser we do more than one task such as querying the database more than once.

So my question is do we have to use async & await as well in _service.GetUser, or is it enough that the caller method do? I'm kind of confused.

    public async Task<UserResponseDTO> GetUser(UserRequestDTO userRequestDTO)
    {
        var userId =  await _utilities.getUserId(); //shall we use it?
        var user = await _dbContext.getFullUserInfo //shall we use it?
           .Where(P => P.userId == userId).FirstOrDefault();
   

        if (!string.IsNullOrEmpty(userRequestDTO.email))
        {
            var emailExists = await _dbContext.getFullUserInfo.Where(p => 
             p.Email == userRequestDTO.email).AnyAsync();  //shall we use it?
        }
    
        await _dbContext.SaveChangesAsync();
        return _mapper.Map<UserResponseDTO>(user);
    }