If we don't want to restrict non-in-person voting back to how it was in 2016

In 2016, several states, including the largest, had either universal mail-in-voting or on-demand permanent-without-special-excuse absentee status, and that number had gone up for 2020 even before the response to COVID prompted some temporary and other permanent changes.

So, what exactly do you mean by “restrict non-in-person voting back to how it was in 2016”?