How to get total supply?

Good day, fellow cryptocurrency enthusiasts! I'm curious about a fundamental concept in the world of digital assets: How exactly do we determine the total supply of a cryptocurrency? Is it a static figure set by the developers at the onset, or does it fluctuate based on certain mechanisms? And if so, what are these mechanisms? I'm eager to understand the intricacies behind calculating the total supply, as it plays a pivotal role in assessing the scarcity and potential value of a coin. Could someone please shed some light on this topic?