Russell Square Tube station

Russell Square is not step free. There is a lift but you also have to deal with stairs. The lift does not go all the way from platform to street level..

Yes, lift from street level to an intermediate level, then 15 or 20 steps down further to the platforms (no escalator).

Thanks!
I’ll go to King’s Cross then.
Hauling even a small suitcase up even a few steps is a pain!

Deep tube stations dating from the pre-escalator era that retain their original lift shafts nearly all have stairs at one or both ends, originally intended as queuing areas. Most these days are not that busy as those that were had escalator conversions, Covent Garden being one exception.

Alternatively you may use Euston Square which, from what I recall, does have a lift to platform level. It's not very far from Russell Square.

Euston Square is served by the Circle, Hammersmith & City and the Metropolitan lines; Russell Square (not actually on the square even if there is a sign there) only serves the Piccadilly Line, so you can reach different destinations.

Thanks.
I only need to know for my arrival from Heathrow, and coming up to ground level that one time.
Otherwise, I’ll be luggage free and don’t mind stairs in the stations.
I’m flying home from Edinburgh.

What @Clyffthear might have meant was that you could use the Elizabeth Line to Paddington, then the Circle or Hammersmith line trains from there to Euston Square, then use the elevator/lift to the south side of the Euston Road, but if KC will work fine for you, as a no change tube route, then that's fine.