Today / Now date in formula

Is there anyway I can include Today or Now in a formula?
I want to compare a specific date field to TODAY date, and if it’s in the past I’ll return false.

The syntax I expected was to be like this:
if(date_diff('dd', field('end_date'), today()) > 0, true, false)


What about doing it like Airtable, they only refresh the NOW() date when someone views the table
or maybe refresh today() date once everyday