  Using 1533 type Ia supernovae (SNe Ia) from the five-year sample of the Dark
Energy Survey (DES), we investigate the effects of projected galactocentric
separation between the SNe and their host galaxies on their light curves and
standardization. We show, for the first time, that the difference in SN Ia
post-standardization brightnesses between high and low-mass hosts reduces from
$0.078\pm0.011$ mag in the full sample to $0.036 \pm 0.018$ mag for SNe Ia
located in the outer regions of their host galaxies, while increasing to $0.100
\pm 0.014$ mag for SNe in the inner regions. In these inner regions, the step
can be reduced (but not removed) using a model where the $R_V$ of dust along
the line-of-sight to the SN changes as a function of galaxy properties. To
explain the remaining difference, we use the distributions of the SN Ia stretch
parameter to test whether the inferred age of SN progenitors are more varied in
the inner regions of galaxies. We find that the proportion of high-stretch SNe
Ia in red (older) environments is more prominent in outer regions and that the
outer regions stretch distributions are overall more homogeneous compared to
inner regions, but conclude that this effect cannot explain the reduction in
significance of any Hubble residual step in outer regions. We conclude that the
standardized distances of SNe Ia located in the outer regions of galaxies are
less affected by their global host galaxy properties than those in the inner
regions.
