The AMD Ryzen 9 7950X3D and Ryzen 7 7800X3D Zen 4 processors would be unlocked for overclocking, according to recent a mention on the AMD product pages. 

Contrary to what has been shared before, this means that the CPUs will feature an unlocked base-clock multiplier, making overclocking easier than on previous-generation Ryzen 7 5800X3D processors with locked base-clock multipliers. The TDP rating of the 16-core/32-thread 7950X3D and the 8-core/16-thread 7800X3D will be 120 W, which is much lower than the 7950X's 170 W rating. Furthermore, the TJmax value is lower, at 89°C, compared to 95°C for the 7950X and 7700X.

These chips will include stacked 3D vertical cache technology (3DV cache). The 7800X3D will include 64 MB of 3DV cache stacked on top of the 32 MB of on-die L3 cache, bringing the total cache (L2+L3) to 104 MB. The 3DV cache memory on one of the two "Zen 4" CCDs will be available exclusively on the 7950X3D and the 12-core/24-thread 7900X3D. The first CCD will contain 96 MB of L3 cache (including the 3DV cache), while the second will be a normal "Zen 4" CCD with only 32 MB of L3 cache on-die. This means that the L3 cache will be 128 MB for the 7900X3D, and the total cache will be 140 MB for the 7950X3D. AMD has stated that their first CPU with 3D V-Cache, the Ryzen 7 5800X3D, is not overclockable due to the limited voltage that can be safely employed in tandem with the stacked L3 cache. 

Currently AMD has altered their product pages to remove this info entirely, implying that the specifications for these chips have not yet been completed.

According to AMD product pages, the upcoming 7950X3D and 7800X3D are Unlocked for Overclocking.