In this question there is discussion of the large differences in temperature between liquid helium-4, subcooled liquid oxygen (sub-LOX) and cold kerosene (RP-1). Approximate temperatures are 4.2K, ~70K also here, and ~286K respectively.
The following question is related to this, but not necessarily based on SpaceX designs or plans.
Above its critical point of 5.2K helium-4 becomes a supercritical fluid where the distinction between liquid and gas no longer applies, and so 'boiling until it reaches equilibrium' is not the right way to think above 5.2K. If you close it off at ambient pressure at 4.2K, it will reach 2.24 atmospheres at 5.19K.
Question: But if you continue to warm this sealed, very strong tank up to 90K (LOX at ambient pressure) or even ~70K (sub-cooled LOX), what would be the helium pressure now?
note 1: that's a supercritical fluid above 5.2K, not to be confused with superfluid.
note 2: since putting tanks of helium-4 inside tanks of LOX has become a critical technology in space exploration, this particular question - what actually happens - should be still considered on topic here.
above x2: Phase diagrams of helium-4 from here.