。
She said it with a warm smile.
Literal
She [topic-は] warmly smile-and so said.
そういった ('said so / said that') is composed of そう ('like that, in that way') + 言った ('said') — a way of referring back to a previously stated content without restating it. This is extremely common in Japanese narrative as a way to keep prose tight without quoting every utterance. The verb 言う often appears in the form いう (in hiragana, often spelled いった for the past) when used in this anaphoric, pointer-like way; the kanji 言う tends to appear when actual speech is the focus. The mimetic にっこり gives the saying its smiling quality.