51k or whatever being fine is not a problem. Everton have just built an entire brand new stadium with that capacity.
They're expanding to 62,000 by Euro 2028.
Edit: they might not be, seems to have just been talk that they were going to.
I was chatting to an Everton season ticket holder the other day. He was telling me that they can expand the North stand to duplicate the South stand, which is the plan to take them to 60k when the time comes.
He also said that they’ve been prevented from hosting concerts there because of fears of getting fans on the pitch out in an emergency. A bit of a silly oversight, if that’s true.