From what I have seen of him, 1-on-1, he is very good for his frame, I would trust him over Couto and Lewis. He kind of knows where you will try to dribble to by studying your movement, because he is a good dribbler, so he anticipates your moves as your try dribble past him.
Depending on the opposition, we can sit him back and push up the LB. If its against the likes of Mbappe, Vini, Mitoma, fast tricky wingers, I would rather see someone who has pace combined with physical built like Van de Ven come in to neutralise the threat. I just don't know how composed he would be against those players. But for his age, he is good!
Since Akanji is more physically built and has dealt with such threats, I would trust Akanji still. It is just my anxiety, not a knock on Tiago's ability!