\input luaotfload.sty
\font\text   ={file:xits-math.otf:script=math}        at 10pt
\font\script ={file:xits-math.otf:script=math;ssty=1} at 7pt
\font\sscript={file:xits-math.otf:script=math;ssty=2} at 5pt
\textfont        4=\text
\scriptfont      4=\script
\scriptscriptfont4=\sscript
\luatexUmathchardef\x="0 "4 "1D465
\luatexUmathchardef\y="0 "4 "1D466

\def\ops{
 \luatexUmathchar "1 "4 "222B\nolimits_{\x}^{\y}
 \luatexUmathchar "1 "4 "222C\nolimits_{\x}^{\y}
 \luatexUmathchar "1 "4 "222D\nolimits_{\x}^{\y}
 \luatexUmathchar "1 "4 "222E\nolimits_{\x}^{\y}
 \luatexUmathchar "1 "4 "222F\nolimits_{\x}^{\y}
}

$$\textstyle\ops$$
$$\ops$$
\bye
