\begin{table}
\centering
\begin{tblr}[         %% tabularray outer open
]                     %% tabularray outer close
{                     %% tabularray inner open
colspec={Q[]Q[]Q[]Q[]Q[]Q[]Q[]Q[]Q[]Q[]Q[]Q[]},
column{1}={halign=l,},
column{2}={halign=r,},
column{3}={halign=r,},
column{4}={halign=r,},
column{5}={halign=r,},
column{6}={halign=r,},
column{7}={halign=r,},
column{8}={halign=r,},
column{9}={halign=r,},
column{10}={halign=r,},
column{11}={halign=r,},
column{12}={halign=r,},
}                     %% tabularray inner close
\toprule
& under_score & oh&yeah<sup>2</sup> & disp & hp & drat & wt & qsec & vs & am & gear & carb \\ \midrule %% TinyTableHeader
under_score         & 1           & .           & .           & .           & .           & .           & .           & .           & .          & .          & . \\
oh&yeah<sup>2</sup> & \num{-.85} & 1           & .           & .           & .           & .           & .           & .           & .          & .          & . \\
disp                & \num{-.85} & \num{.90}  & 1           & .           & .           & .           & .           & .           & .          & .          & . \\
hp                  & \num{-.78} & \num{.83}  & \num{.79}  & 1           & .           & .           & .           & .           & .          & .          & . \\
drat                & \num{.68}  & \num{-.70} & \num{-.71} & \num{-.45} & 1           & .           & .           & .           & .          & .          & . \\
wt                  & \num{-.87} & \num{.78}  & \num{.89}  & \num{.66}  & \num{-.71} & 1           & .           & .           & .          & .          & . \\
qsec                & \num{.42}  & \num{-.59} & \num{-.43} & \num{-.71} & \num{.09}  & \num{-.17} & 1           & .           & .          & .          & . \\
vs                  & \num{.66}  & \num{-.81} & \num{-.71} & \num{-.72} & \num{.44}  & \num{-.55} & \num{.74}  & 1           & .          & .          & . \\
am                  & \num{.60}  & \num{-.52} & \num{-.59} & \num{-.24} & \num{.71}  & \num{-.69} & \num{-.23} & \num{.17}  & 1          & .          & . \\
gear                & \num{.48}  & \num{-.49} & \num{-.56} & \num{-.13} & \num{.70}  & \num{-.58} & \num{-.21} & \num{.21}  & \num{.79} & 1          & . \\
carb                & \num{-.55} & \num{.53}  & \num{.39}  & \num{.75}  & \num{-.09} & \num{.43}  & \num{-.66} & \num{-.57} & \num{.06} & \num{.27} & 1 \\
\bottomrule
\end{tblr}
\end{table} 
