Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Microchip Technology/ATSAME51J19A/SERCOM0/SPIS/CTRLC#0x0
DATA32B=DATA_TRANS_8BIT
SPIS Control C
Inter-Character Spacing
Data 32 Bit
0 (DATA_TRANS_8BIT): Transaction from and to DATA register are 8-bit
1 (DATA_TRANS_32BIT): Transaction from and to DATA register are 32-bit
https://github.com/cmsis-svd/cmsis-svd-data