How to combine 2 expression into 1 ?

You aren't going to be able to do that with a calculated column since each year can only belong to at most one of 3 or 4.

You can approach this in a different way though and create a new parameter table to use for the slicer and then define a measure to use as a filter on your date slicer.

For the option to select 1-5 years back, define a new calculated table like this:

ShowLast = SELECTCOLUMNS ( GENERATESERIES(1, 5), "Year", [Value] )

Then you can define a measure like this which you'll then set as a visual filter for the date table year slicer:

YearFilter = 
VAR SelectedYear = SELECTEDVALUE ( ShowLast[Year], MAX ('Date'[Year] ) )
VAR CalendarYear = MAX ( 'Date'[Year] )
RETURN
    IF ( YEAR ( TODAY() ) - CalendarYear <= SelectedYear, 1, 0 )

See the attached file.