\documentclass{article}
\usepackage{unicode-math}
\setmathfont{xits-math.otf}

\begin{document}

\[
	\mathrm{L^2} \quad \mathrm{L^2_2} \qquad \textstyle \mathrm{L^2} \quad \mathrm{L^2_2}
\]

\[
	\mathrm{A^2} \quad \mathrm{A^2_2} \qquad \textstyle \mathrm{A^2} \quad \mathrm{A^2_2}
\]

\[
	\mathrm{F^2} \quad \mathrm{F^2_2} \qquad \textstyle \mathrm{F^2} \quad \mathrm{F^2_2}
\]

\[
	\mathrm{V^2} \quad \mathrm{V^2_2} \qquad \textstyle \mathrm{V^2} \quad \mathrm{V^2_2}
\]

\[
	\mathrm{W^2} \quad \mathrm{W^2_2} \qquad \textstyle \mathrm{W^2} \quad \mathrm{W^2_2}
\]

\[
	\mathrm{P^2} \quad \mathrm{P^2_2} \qquad \textstyle \mathrm{P^2} \quad \mathrm{P^2_2}
\]

\[
	\mathrm{T^2} \quad \mathrm{T^2_2} \qquad \textstyle \mathrm{T^2} \quad \mathrm{T^2_2}
\]

\[
	\mathrm{\Gamma^2} \quad \mathrm{\Gamma^2_2} \qquad \textstyle \mathrm{\Gamma^2} \quad \mathrm{\Gamma^2_2}
\]

\[
	\mathbf{L^2} \quad \mathbf{L^2_2} \qquad \textstyle \mathbf{L^2} \quad \mathbf{L^2_2}
\]

\[
	\mathbf{A^2} \quad \mathbf{A^2_2} \qquad \textstyle \mathbf{A^2} \quad \mathbf{A^2_2}
\]

\[
	\mathbf{F^2} \quad \mathbf{F^2_2} \qquad \textstyle \mathbf{F^2} \quad \mathbf{F^2_2}
\]

\[
	\mathbf{V^2} \quad \mathbf{V^2_2} \qquad \textstyle \mathbf{V^2} \quad \mathbf{V^2_2}
\]

\[
	\mathbf{W^2} \quad \mathbf{W^2_2} \qquad \textstyle \mathbf{W^2} \quad \mathbf{W^2_2}
\]

\[
	\mathbf{P^2} \quad \mathbf{P^2_2} \qquad \textstyle \mathbf{P^2} \quad \mathbf{P^2_2}
\]

\[
	\mathbf{T^2} \quad \mathbf{T^2_2} \qquad \textstyle \mathbf{T^2} \quad \mathbf{T^2_2}
\]

\[
	\mathbf{\Gamma^2} \quad \mathbf{\Gamma^2_2} \qquad \textstyle \mathbf{\Gamma^2} \quad \mathbf{\Gamma^2_2}
\]
\end{document}