“Most toilets that have tanks use a ballcock that is designed to allow a very small trickle of water to constantly go into the bowl to avoid having the water stagnate.”
water goes back into the bowl after a flush at the same time the tank is filling.
once the ballcock shuts off, both outflows are stopped completely, unless you have a malfunctioning toilet.
that is for the common ballcock setup. perhaps there are some models that allow a constant trickle continuously but i highly doubt it. that would generally be referred to as a “leak”. a setup like that, which ive never seen, would run counter to most local water conservation codes.