"I imagine your life will change drastically if you were to get full marks on the TOEIC exam."
「劇的に」には "dramatically" と "drastically" はどちらもネイティブで使われています。
"I imagine your life will change drastically if you were to get full marks on the TOEIC exam."
"I imagine your life will change ~" 「人生が変わるんだろうなぁ」
"your life will change drastically" 「劇的に人生が変わる」
"if you were to get full marks on the TOEIC exam." 「TOEICで満点とったら」
"full marks" 「満点」
"get full marks" 「満点とる」
"TOEIC exam" 「TOEIC試験」