I picked it up that he was planning to apply, so if he got a new passport before applying then the visa would be in the new passport. Admittedly, I'm not sure of his use of terminology. Maybe he already has a 90 day visa and is meaning a year extension 🤷♂️
check with the airline. I was in the same situation, had a 60 day tourist visa and a 90 day return ticket. Flew with Thai Airways without any issues of needing to show onward travel within 60 days.