Well, actually, sort of and sort of not.
See the post of @Modiphius-Nathan I linked in a posting above on the reasoning behind STA’s differentiation between “Chief Security Officer” and “Science Officer”. I think it is, in part, due to some debate of whether Spock was Kirk’s science officer or the Chief Science Officer of the Enterprise. I cannot comment on how he was referred on-screen, because I think I never watched TOS in english. I recall Kirk refer to him as his science officer in the translations, but those translations were inaccurate in the 60ies and are still terrible, today (it’s funny, though, when you can derive the original-language dialogue from an out-of-context mistranslation: “they totally said xyz in the original dialogue but f*cked up translation!”).
Yet, both explanations are intuitively plausible. And it might even be that both are true; e.g. in a sense that some smaller ships without a genuine scientific purpose or task do have a designated “chief science” in charge of a specialised group of scientists aboard (take e.g. a Pathfinder/Reconnaissance Defiant with a small team of stellar cartographists) while larger ships, especially those built for science missions (take a Sovereign class built for scientific and survey operations) have multiple science departments with multiple department heads (chief of stellar cartography, leader of the xeno-linguistics team, head of geologists and arechologists etc.) and one science officer on the bridge functioning as some kind of a liason in between those and the captain.
Ultimately, I’d recommend to ask the “Question 0 of STA”: What would support Drama? and give the answer a thorough try.