That depends
Some people in England may use more and most for even the monosyllabic adjectives like clean, pure the aforementioned speech may stand you in good stead if your target is to know how to write in your exams but if if you like to explore further afield, you would sooner use more and most than the inflected form. That's when your comparison is not between two nouns but is used to serve such a function as it does when you say he is more wealthy than I thought. In such an example the periphrastic form is given priority

Second, if your comparison is polarized between two nouns you should also use the periphrastic form viz he's more a poet than a novelist[/i

Nevertheless as a second year student you can do with the already offered information