Ideal Switching Signal for a Featherwing power Relay board
No, any voltage above 0.7V will not cause the "switch to switch". You need to think about how much current the relay needs, and how much current must flow into the base of the transistor.

Now, the relay needs 100mA and lets assume that the \$h_{fe}\$ of the transistor is at least 50. That means you need at least 2mA into the base of the transistor to get 100mA to the relay.

Assume that the base-emitter voltage is 0.7V, which means that 0.07mA flows through R2 to ground. By KCL we need at least 2.07mA to flow through R1, and by Ohm's Law that means the voltage across R1 must be at least 2.07V. Using KVL, the input voltage must be the voltage across R1 plus the voltage from the base to emitter, for a total of 2.77V. This was all back-of-the-envelope estimation, but I would say that the input needs to be above 3V to reliably "switch the switch". You want to provide enough base current that the transistor goes into saturation in order to minimize power dissipation (and heat).