Create a segment using the Days Since Last Visit dimension
Use a hit container, "is greater than" as the comparison operator, and "7" as the value associated with the comparison operator.
You are using 7 as the value because ITP 2.1 is supposed to reset cookies for visitors who don't come back within 7 days. ITP 2.2, which was announced in late April 2019, has changed this to 1 day rather than 7.
Create a calculated metric using your Days Since Last Visit > 7 segment
I like having a calculated metric for this since it makes things look cleaner. You can use "visits" as the metric when building this.
Create a calculated metric for % Days Since Last Visit > 7
Take your Days Since Last Visit > 7 calculated metric and divide it by visits. I prefer using a percentage rather than decimals If you apply this calculated metric to days in Analysis Workspace, you will see the percentage of visits on a given day that
Create a segment for Apple browser visits
Since ITP impacts Apple browsers (Safari), create a segment that focuses solely on these. You can use a visit container with Browser Type as the dimension, equals as the operator, and a value of "Apple".
You'll probably want to set up a few freeform tables in Analysis Workspace to see what happens with these calculated metrics: