Nuances of meaning between "comme ça" and "tant/plus que ça"

Question

Je n’en ai peut-être pas l’air comme ça mais je suis un ...

I just heard one of my colleagues use "comme ça", possibly with the meaning of "not ... all that much". If so, how does it compare to saying "pas ... tant que ça" or "pas ... plus que ça"?

Je n’en ai peut-être pas l’air tant que ça mais je suis un ...

Je n’en ai peut-être pas l’air plus que ça mais je suis un ...

Je n’en ai peut-être pas plus l’air que ça mais je suis un ...

Incidentally, I suppose "comme ça" can be used both in affirmative and negative sentences, whereas "tant/plus que ça" are reserved mainly for negative contexts.

Answer 1

Je n’en ai peut-être pas l’air comme ça mais je suis un …

In this sentence "comme ça" means "at first sight" or any other similar term. It means that we couldn't expect that from you without knowing you a bit. For instance "Je n'ai pas l'air timide comme ça, mais en fait j'ai beaucoup de mal à parler aux gens" could be translated as "I know I don't seem shy but I have a lot of trouble talking to people".

Je n’en ai peut-être pas l’air tant que ça mais je suis un … There, "tant que ça / plus que ça" are synonyms and mean "not … all that much".

Note : "pas l’air plus que ça" and "pas plus l’air que ça" are the same and the words can be put in any of the 2 orders. The second one seems more correct to me but the first one is more used in real life.