SetStyle
function SetStyle(oStyle: ApiStyle = null): ApiRange | "null"Description
Sets the style to the current Range.
Parameters
The style which must be applied to the text character.
Returns
ApiRange | "null"Try It
var oDocument = Api.GetDocument();
var oParagraph = oDocument.GetElement(0);
oParagraph.AddText("ONLYOFFICE Document Builder");
var oRange = oDocument.GetRange(0, 26);
var oStyle = oDocument.GetStyle("Heading 2");
oRange.SetStyle(oStyle);