Is expiation or making up (the fast) obligatory upon a young man who ruined two days of Ramadan due to his addiction to "hot calls" and the emission of semen?

You must make sincere repentance, regret the sin, and resolve not to return to it. There is no expiation due upon you, as it is only obligatory, according to the preponderant opinion, for breaking the fast through intercourse. It is more cautious to make up the two days because the emission of semen was caused by you, resembling repeated looking which necessitates making up the fast according to many scholars.