When will /e/ support Galaxy S20 or S21 newer phones?

https://community.e.foundation/search?q=S20

As your device is compatible zith the projet treble, you can

install the official /e/ GSI (Generic System Image)

https://doc.e.foundation/support-topics/understand-and-use-gsi.html

Or a device specific build, here is a test one

[UNOFFICIAL BUILD] Samsung S20 Exynos e0.23