In my experience, not much of anything. I tone 1:9 in KRST or 1:24
Polytoner for ~5 minutes.

It must depend on the paper. My MFA thesis show ~15 years ago had a series
of prints variously affected by pot. ferricyanide and selenium toner in all
sorts of combinations.

On 1:8 selenium toned prints on now-extinct Portriga Rapid paper, bleaching
would produce pronounced orangish-sepia tones. I still have a few of those
prints around the house.

I guess the best answer for the original poster would be to try it on a test
print.

Bill Schneider