Currently, the time aggregation level can only be modified in the analysis, not the dashboard.
So to allow end users to change a visual’s level between day/week/month, I’ve been using a control/parameter/calc field combo as described in this post. The parameter is linked to a control, which allows the user to select between the granularity levels in a dropdown (strings I typed in). And the calculated field formats a date according to the level selected via the dropdown, i.e. when month is selected, 1/15/22 is formatted as 1/1/22.
It’s definitely a workaround because for it to work neatly, I need to disable gaps in time. For example, the visual is set to Day level aggregation, and with the calculated field set to Month, the visual will contain dates belonging to the first of the month. But due to the Day level aggregation, I either disable gaps and the visual is neat, or I don’t and the visual shows every Day in the month - unnecessary dates with no data. Disabling gaps would hide those days in between, i.e. 1/2-1/31, but it would also hide if there were no data in a month, i.e. 2/1.
tl;dr
It’d be really cool if the time aggregation level that’s editable in the field well could also be edited in the dashboard by end users. Or alternatively, if a parameter/control could modify the time aggregation level.