Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Microchip Technology/ATSAME51J19A/SUPC/VREG#0x0
SEL=LDO
VREG Control
Enable
Voltage Regulator Selection
0 (LDO): LDO selection
1 (BUCK): Buck selection
Run in Backup mode
Voltage Scaling Enable
Voltage Scaling Period
https://github.com/cmsis-svd/cmsis-svd-data