You want it the same size as the text around it? usually the font of a superscript IS smaller than the surrounding text. Certainly if you superscript text in word, that is what happens?
see image attached. in the first line, I inserted a superscripted EndNote (Nature output style) then I followed it with some text and used word to superscript it. (I then highlighted the EndNote inserted 1 in yellow).
In the second line, I inserted “1now is the time” and superscripted it all with word.
Not a lot of difference. If anything the endnote one is very slightly larger? – Word still shows the superscript of all of the above as 11 pts.
What are you looking for?