Any way to set "--csv" in BEGIN?

[Ed Morton]

I'm loving the new "--csv" option for CSV parsing in gawk 5.3, thanks, 
but I don't see anything in the documentation about specifying the input 
is CSV from inside an awk script so, in case I'm just not seeing it - is 
there any variable we can set or any other way to specify the equivalent 
of "--csv" from inside an awk script, e.g. in a BEGIN section, like we 
can set RS, FS, FPAT, and/or FIELDWIDTHS for the existing types of input 
parsing?

    Ed.