Splitting the difference with the 24" might work for me, too, but I have been satisfied completely with the 21.5" since 2019.
Personally I have become hooked on having two displays, so should you ever consider adding a second display, two 24" displays are significantly less overwhelming than two 27" displays, not to mention less expensive.
FYI: The builtin monitor on M1 iMacs, MacBook Pros, ands MacBook Airs is an HDMI connection so the external monitor can be up to a 6K display with any interface supported via Thunderbolt 4 (Thunderbolt 3 or display port, and with appropriate adaptors HDMI, VGA, DVI or thunderbolt 2)
