Typically I’ve seen people keep their car in 2nd (or reverse IIRC? That way your controller doesn’t have to support reverse and you don’t have to put in a new switch on the dash) in electric swaps. Also you don’t use the clutch pedal to start, only to change gears, which is a bit freaky when you’re not used to it.
On the highway there might be value in switching to a higher gear though, torque/efficiency curves aren’t perfectly flat even on electric motors. I would be curious to know what gains would be had on a modern electric platform like an ID.3 if one was to put in a cheap two or three gears sequential/manual transmission (for all I know the efficiency gains would not offset the additional losses from the clutch and gearbox, and even if they are some gains I’m sure that they do not make up for the inconvenience/lack of comfort of a MT).