You could use Graduated Colors, but that wouldn't be dynamic.
You could probably rig something up with a calculation attribute rule. Add an integer field. When you insert/delete a feature or when you update the Sequence field, get the minimum Sequence value of the featureset, then update the new field of all features to 0 or 1, depending on whether their Sequence is the lowest. Symbolize with Unique Values on the new field.
It might be easier to just add the layer to the map a second time and set its definition query:
Sequence IN (Select MIN(Sequence) AS SmallestSequence FROM DatabaseName.DataOwner.TableName)
This will only show the feature(s) with the smallest Sequence value. Then you can use that layer to highlight these features:
Have a great day!
Johannes