A topic covered among the first few sections of e-bikes 101: Understanding the difference between Throttle and Pedal Assist (PAS / Pedelec).
Each mode has it's own set of pros and cons to its usage. Truth be told, you see a lot of e-bikes offering both anyway.
But understanding some of the nuance for use case, and certainly legalities, is worth learning about or refreshing if you already know.
Head to the link below for a more detailed look at the different e-bike modes.