Uhmm, I think that 40 is the limit 
If you see the processor specifications on https://ark.intel.com/content/www/us/en/ark/products/120489/intel-xeon-gold-6148-processor-27-5m-cache-2-40-ghz.html
It is 20 cores so it it's only 40 threads max.
I am not hardware expert so if you believe that your processor can be overclocked or something like that I think that you should search about it on a Hardware forum or something like that.
If you see the processor specifications on https://ark.intel.com/content/www/us/en/ark/products/120489/intel-xeon-gold-6148-processor-27-5m-cache-2-40-ghz.html
It is 20 cores so it it's only 40 threads max.
I am not hardware expert so if you believe that your processor can be overclocked or something like that I think that you should search about it on a Hardware forum or something like that.
2 cpus at 40 threads, 80 total. CPU info shows 80 possible. Ubuntu shows 80 threads. But you may be correct. Strange as bios reports 40 however its not clear if its reporting for 1 cpu or 2.
Again thank you for all the hard work!