Portions size options, yes, because :
A) As long as they are priced accordingly, then It's ok
B) Please don't assume age = reduced appetite (ok, I'm on Gransnet, but I'm 58 and a right piggy when it comes to some things!
But in all seriousness, coming up with a viable menu for a pub (or anywhere, for that matter) is a challenge.
You have to be affordable, serve things that people want to eat whilst still keeping an eye on profit.
Plus looking at demand versus possible wastage.
Perhaps do some standard things that can be bulk cooked and frozen down in portions, then a few "specials of the day" , limited to perhaps 6,8, portions of each, (when they've gone, they've gone!) This would obviously depend on the usual trade at the particular establishment.
Another thought, seasonal! I saw leek and potato soup on a pub menu in July!!!
WRONG! That is an Autumn/Winter soup