Get date from other table columns

Yqy , If you need a two columns

Min(Table[Start])

Max(Table[End])

If you need as two measures

Minx(allselected(Table) , Table[Start])

Maxx(allselected(Table) ,Table[End])

If you want default a range based slicer , create a calendar with those date, I doubt you can initialize range based slicer

calendar(

Min(Table[Start]) , Max(Table[End]) )

the calender one works thank you