Photons to Photos posted this DxOmark derived Sony A7rIV dynamic range measurement. As you can see the performance is about the same as on the previous A7rIII model.
Sony A7rIV and new accessories:
Sony A7rIV in USA/CA at BHphoto, Adorama, FocusCamera, Amazon, Henrys.
Sony A7rIV in EU at Calumet DE, ParkUK, WexUK, Calumet NL.
Sony A7rIV in Asia at Sony Japan. Sony Australia.
Sony VG-C4EM grip in USA at BHphoto, Adorama, Amazon, FocusCamera, ParkUK, WexUK.
ECM-B1M Digital Audio Shotgun Microphone at BHphoto, Park UK.
XLR-K3M Mic at BHphoto, Park UK.