Marc Alhadeff made this graph showing the best lenses to achieve maximum sharpness for your Sony A7rIV. Marc is known for making a ton of FE lens reviews and is one of the few that can therefore give you this complete overview!
The very best you can get are:
Sony FE 135mm f/1.8 GM at Amazon, BHphoto, Adorama. Amazon DE. Amazon UK.
Sony 24mm f/1.4 GM at Bhphoto. Adorama. Amazon. Amazon DE. Amazon UK.
Zeiss 5omm f/1.4 lens at Amazon, Adorama, BHphoto. Amazon DE. Amazon UK.
Sigma 105mm f/1.4 at BHphoto, Amazon, Adorama. Amazon DE. Amazon UK.
Sigma 35mm f/1.2 FE at Adorama, BHphoto, Amazon, Amazon DE. Amazon UK.
Sony 400mm GM at BHphoto, Adorama, Amazon, Amazon DE. Amazon UK.
Sony 600mm FE GM in USA at Amazon, BHphoto, Amazon DE. Amazon UK.
Voigtlander 65mm f/2.0 FE at BHphoto, Amazon, Adorama. Amazon DE. Amazon UK.
Voigtlander 110mm f/2.5 FE at BHphoto, Amazon, Adorama. Amazon DE. Amazon UK.
So technically speaking the best lens I do own is the Sony 85mm f/1.8 FE…maybe it’s time for me to consider to get at least one lens of the top pool :)