We've not had a lot of luck when manually overclocking the other RTX 3080 cards we have tested, but we did slightly better with the TUF Gaming. We managed to add 70MHz to the GPU core, and 900MHz to the GDDR6X memory.
This overclock still didn't bring us huge real-world gains, as we saw an extra 5% performance in Gears 5, 4% in Ghost Recon: Breakpoint, and 3% in Total War Saga: Troy.