The National JR pass can be used on Narita Express and some of the trains between Tokyo and Shin-Osaka. It isn't valid on the fastest and most frequent shinkansen "Nozomi" between Tokyo and Shin-Osaka. Most tourists are fine with that given the cost savings and the second fastest bullet train frequency is still roughly every hour.
JPRail.com is a great resource for digging into JR pass validity & even some of the "how to make this transfer" info
Narita Info
https://jprail.com/travel-informatio...own-tokyo.html
How to get good value for a JR Pass (but with seniors with mobility challenges, bear in mind this is written by a younger person who loves trains)
https://jprail.com/travel-informatio...s-maximum.html