Complementing above explanation on CC and CV mode.
Both are always standby until the load reached set point by max voltage and/or max current allowed.
But why when you start powered on the PSU is on CV mode ? Not in CC mode ?
That is because "
most of the times" the load is not connected or turned off, hence the PS in CV mode is on as almost no current consumed, or even the load is on, its still under max current set, and CC mode is off by nature in that condition.
Just try hook up a piece of thick wire to short circuit the PS output, yes, its safe for the PS as long you're watching and attending it as that wire may get hot or turns red.
And possibly catch fire too if left for too long.
That is a crude way to test a PSU which has CC mode, and its perfectly safe for the PSU, although not for your house/table if the load/poor wire catch fire.
Watch the PS with that condition, it will instantly switched into CC mode as the load suck current like hell until it reached max current set point , and as the load is really low resistance (aka short circuit), also watch the voltage as it will drop like a rock, no matter how high you set, hence in that situation, CV mode is off and CC mode kicks in.
These are fundamentals of Ohm law Volt = Current x Resistance (load) , suggesting to learn and understand it, and your question will become irrelevant.