Using Firths penalized likelihood instead of the ordinary likelihood is an option in the model statement in proc logistic. It is still binary logistic regression so it is not right to say that you instead use Firths likelihood. Here is a simple example
data mydata;
input n x exposure;
cards;
100 10 0
100 5 1
;
run;
proc logistic data=mydata;
class exposure(ref="0")/param=glm;
model x/n=exposure/firth;
run;
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