Just for fun:
The term “electric piano” generally refers to electromechanical pianos, like the Wurlitzer A100, Rhodes, or Yamaha CP70 (“electric baby grand”). I had a CP70 for decades, and still have the Rhodes I bought new in 1978. Electric pianos do not have a transpose feature.
In common parlance, “Electronic pianos” have analog electronics, and most agree that they were horrid, although some great music was still made using them, such as early Genesis’s use of the RMI ElectraPiano – an instrument that makes me gag, but in the hands of a master, is indeed a worthy tool. (Tony Banks replaced it with a CP70 when they became available.) I don’t know whether the typical electronic pianos had a transpose feature; I wouldn’t be surprised either way. I was never unlucky enough to own one myself, but I know a few guys who still groan about theirs.
What we use today are called “digital pianos”. Most (possibly all) DPs have a transpose feature. On some, it’s very convenient and easy to use live. In others, it requires menu diving. Most self-respecting keyboard players eschew their use, citing cases where someone played a beautiful, elaborate intro, only to find out it was in the wrong key as the rest of the band comes in (having accidentally left the transpose feature on). The masters can play nearly anything in nearly any key without batting an eye. Upside down and backwards, too.
I’m no master; I might not even qualify as self-respecting. I use it occasionally, and so far (knock on wood) haven’t had the intro fiasco. However, one time at a jam I did accidentally leave it turned on for the guy playing the next set. Oops! Fortunately I saw what was going on and quickly fixed the situation. No careers were ruined.