  We present results for the axial-vector coupling and root-mean-square (RMS)
radii of the nucleon obtained from 2+1 flavor lattice QCD at the physical point
with a large spatial extent of about 10 fm. Our calculations are performed with
the PACS10 gauge configurations generated by the PACS Collaboration with the
six stout-smeared $O(a)$ improved Wilson-clover quark action and Iwasaki gauge
action at $\beta$ = 1.82 and 2.00 corresponding to lattice spacings of 0.085 fm
and 0.063 fm, respectively. We first evaluate the value of the axial-vector
coupling of the nucleon ($g_A$). In addition, the isovector electric, magnetic
and axial radii and magnetic moment from the corresponding form factors are
also determined. Combining the results at $\beta=1.82$ and $2.00$, we finally
discuss the finite lattice spacing effect. It was found that the effect on
$g_A$ is kept smaller than the statistical error of 2% while the effect on the
isovector radii was observed as a possible discretization error of about 10%,
regardless of the channel.
