Borrowed this from another forum, it makes for an interesting read. These are siliconeLottery's findings.

As of 11/17/18, 100% of tested 9900Ks were able to hit 4.8GHz or greater.
CPU Multiplier: 48
BCLK: 100.0
CPU Vcore: 1.275V
AVX Offset: 2

As of 11/17/18, the top 82% of tested 9900Ks were able to hit 4.9GHz or greater.
CPU Multiplier: 49
BCLK: 100.0
CPU Vcore: 1.287V
AVX Offset: 2

As of 11/17/18, the top 46% of tested 9900Ks were able to hit 5.0GHz or greater.
CPU Multiplier: 50
BCLK: 100.0
CPU Vcore: 1.300V
AVX Offset: 2

As of 11/17/18, the top 14% of tested 9900Ks were able to hit 5.1GHz or greater.
CPU Multiplier: 51
BCLK: 100.0
CPU Vcore: 1.312V
AVX Offset: 2

There are no 5.2GHz chips being offered and the settings and frequencies above are with non delidded CPUs.

With regards to delidding they say that "Peak core temperatures under a heavy overclocked load typically decrease anywhere from 4°C to 8°C for Intel 9th generation CPUs."

Takeaways from this, 1 in 5 9900ks tops out at around 4.8GHz.

More than 50% of 9900ks wont reach 5GHz(!)