While there certainly are fares which retain full value even in the case of a no show, they are typically at the very high end of the spectrum. Even refundable and changeable fares without the pandemic waiver require cancellation prior to scheduled flight in order to retain value.

OP should certainly check the fare rules for each segment, but I will be surprised if he has anything but a "standard no show = cancellation and loss of value" provision. The question then is whether and how quickly this occurs. The answer is unknown and not predictable because it is a software-based rather than policy issue.

Right now with the pandemic waiver, there is absolutely no circumstance where one would not cancel and take the refund or credit as there is no penalty for doing so. In better times, one might risk this if the fees are high.