In the same way that you can build the html for the cells of the table, just write an expression for one of the output columns to include the style attribute that you want based on a condition. For example, instead of
select myCol1, myCol2, someOtherCOl
from myTable
you'd use
select
case
when myCol1 > someOtherCol
then '<b>'+myCol1+'</b>'
else myCol1
end as myCol1
, myCol2, someOtherCOl
from myTable
The conditional part after the "when" can be anythnig that evaluates as a boolean, so it could use = for an exact text match or "like" for a pattern match.