Hi
I will give this to you as a two part formula for ease and clarity but obviously can be nested one inside the other
so to get the days between now and renewal - Calculation of days to renewal is defined as
DATETIME_DIFF(Notes,TODAY(),‘days’)
then you can have a second formula
IF(Calculation<0,“Needs Renewal”,IF(Calculation<21,“Close to Renewal”,“OK”))
This obviously gives your field as a formula - if you want it to be anything else (e.g. single select field) - then you will need to use automations based on the results of those formulae and potentially views to trigger