Column with formula to be edited when user selects "custom"

[guasi]

I'm new to AppSheets and this forum. I'm wondering if it's possible for the value of a column to be the result of a formula, which includes an option to be editable by the user.

I have a filterdate table, with three columns, Filter (enum), Start (Date), End (Date). Right now, upon selection of the Filter value (All Dates, This Month, This Year, Last Month, Last Year), a formula calculates the value for Start and End.

The formula for Start looks like this

IFS(
([Filter] = "All Dates"),  MIN(transactions[Date]),
([Filter] = "This Month"), EOMONTH(TODAY(), -1) + 1,
([Filter] = "This Year"),  DATE(CONCATENATE("01/01/",YEAR(TODAY()))),
([Filter] = "Last Month"), EOMONTH(TODAY(), -2) + 1,
([Filter] = "Last Year"),  DATE(CONCATENATE("01/01/",YEAR(TODAY())-1))
)

It all works fine, but I wanted to add an option "Custom" to allow the user enter Start and End date fields.

Is that possible?