You need to check on the benefit page.

https://www.interrail.eu/en/plan-your-trip/pass-benefits

Thank you for your help. I have checked and there are no discounts available for museums. Nevermind, I'm sure we will see everything we need to. 

I see a few railway museums and one art museum. Filter for "Attractions”.

Thank you for your help. 

There are often museum passes for regions or countries available. Depending on how long you stay in a country and how many museums you plan to visit, that might pay off.

Examples: The Netherlands Museum Pass, Swiss Museum Pass

Once when they did heavy promotion/changed the scheme all national railway museums got included-this has slowly petered off. As a general rule NO discounts for museums. IF they offer-it will often depend on age and in some countries there are also free days/times-but sometimes only for locals. If you intend to visit a lot, you have to inquire for each-or perhaps a general touristy forum like tripadvisor may contain already more.

Also note that as a heritance of covid many still want you to pre-reserve time slots for visits.

Thank you for your help.  Really appreciate it.