No, steady state does not mean that the values cannot change from what they were at time = 0 (i.e. when you turned the PC on). It means the values have settled at some final value once some steady load has been applied for some time.
E.g. you start running Prime95. Your CPU temp starts rising rapidly but eventually levels out after you've run it for a while. You are now at steady state. At this point the heat being dissipated is equal to power draw. In other words, if your temp is not changing then heat dissipation must equal power draw. If they weren't equal, then temp would keep increasing indefinitely. Or in this case, until your CPU overheated and throttled, thereby reducing power draw such that it's lower than or equal to dissipation.