Page dimensions

you should make a die line, since the paper needs to be cut following a die line.

Make the hexagon of the size that it needs to be on to a page size bigger than the hexagon to allow for bleed. make that on a master and layout on a seperate layer.

I wrote a step by step here

https://creativepro.com/creating-keylines/

You will need it to be a spot colour and for it to be set to overprint. 

The same principle is in play - it's a hexagon shape instead. 

Ask your print provider before going any further.

Your best bet would be to consult the output provider as to exactly how they'll want it set up to best facilitate their process. It's likely you'll have to make the page size a square of the same height/width of your final hexagon-shaped trim, then add a hexagon shape stroked with a particular non-printing spot color to serve as the die or laser-cut line. Don't forget to account for bleed, if applicable.

It is not possible: you have to put a die-cut line on the master page, using a spot colour.