You should be able to use the max operator for this, so to get a single line:
Current cell’s (on the parents RG) design line item’s binary:max

To get the highest number on the whole page it’d be something like:
Rg design’s design line items:each item’s binary:max:max

And if that’s not an option for the whole page, use format as text with a comma delimiter:
Rg design’s design line items:each item formatted as text(this line item’s binary:max):split by(,):each item converted to a number:max