You just need to combine the filter using AND OR and wrap each in parentheses ().
(Statement AND statement) OR (Statment2 AND Statement2)
If your TerminationNotice is a number type column then the number is by itself without ' single ' quotes:
(TerminationDate eq 'formatDateTime(addDays(utcNow(),30),'yyyy-MM-dd')' AND TerminationNotice eq 30) OR
(TerminationDate eq 'formatDateTime(addDays(utcNow(),60),'yyyy-MM-dd')' AND TerminationNotice eq 60) OR
(TerminationDate eq 'formatDateTime(addDays(utcNow(),90),'yyyy-MM-dd')' AND TerminationNotice eq 90)
If your TerminationNotice column is a single line text then the numbers need ' single ' quotes:
(TerminationDate eq 'formatDateTime(addDays(utcNow(),30),'yyyy-MM-dd')' AND TerminationNotice eq '30') OR
(TerminationDate eq 'formatDateTime(addDays(utcNow(),60),'yyyy-MM-dd')' AND TerminationNotice eq '60') OR
(TerminationDate eq 'formatDateTime(addDays(utcNow(),90),'yyyy-MM-dd')' AND TerminationNotice eq '90')
Try this in your Filtery Query.

Just make sure the spaces are correct and doesn't use line breaks.