Γεια σου! Χρόνια πολλά και ευτυχισμένο το 2017!
Emphasis in Greek is given, as in almost all languages with the sound of our voice and the intonation. This relates to oral speech, of course.
In the example you gave, we would say in Greek:
"αυτός έχει δοκιμάσει τα πάντα στη ζωή του, και όταν λέω τα πάντα εννοώ τα πάντα."
In oral speech we would give emphasis on the word πάντα with the intonation and timbre of our voice. The addition of the expression "και όταν λέω τα πάντα εννοώ τα πάντα" gives extra emphasis in oral speech , and it also works strongly to the written word. So, we wouldn't add or change anything in a sentence like this, because it is already emphatic.
In general, when we write in Greek, we can emphasise on something by changing the order of words. We put the word that we want to emphasise on in the beginning of the sentence. We can play with the word order in oral speech as well.
Δεν πηγαίνω ποτέ βόλτα στο κέντρο. Ι never go for a walk in the center.
In this sentence the word order is normal and we do not put special emphasis on something.
But if we put the word "ποτέ" first , the emphasis goes on it.
Ποτέ δεν πηγαίνω βόλτα στο κέντρο. = I never go for a walk in the center.
If we put the word "κέντρο" first, the emphasis is on it.
Στο κέντρο ποτέ δεν πηγαίνω βόλτα. = In the center I never go for a walk.
If we add the personal pronoun(which is usually omitted) at the beginning, then the emphasis changes.
Εγώ ποτέ δεν πηγαίνω βόλτα στο κέντρο. = I do not ever go for a walk to the center.
Of course, although there is much flexibility in the word order in Greece, we cannot change it without following the rules of Greek syntax.