The 10850H has a 45W TDP rating so a properly engineered laptop with this processor should be able to run at up to 45W without the CPU overheating or thermal throttling. Your screenshot shows a max temperature of one core of 95°C while the cores beside it are only at 76°C and 77°C even though all cores are running the exact same TS Bench task. That is almost always a sign that there is a problem with the heatsink. Have you ever done any maintenance? If blowing out the dust with compressed air does not lower the temperatures then consider replacing the thermal paste with Honeywell PTM 7950.
Dell Precision laptops used to be big rugged beasts with plenty of performance and excellent cooling. The 3551 is listed as a Lightweight Workstation. It is possible that Dell compromised the excellent cooling of previous models. Thin and light laptops are not the best when it comes to maximum performance. Your CPU is overheating when power consumption is only 35W.
Your CPU is also power limit throttling when power consumption is only at 20W. If you look in the TPL window you will see that the MMIO PL1 power limit is set to only 20W. That is why you are seeing power limit throttling at such a low power consumption value. I would check the MMIO Lock box to get rid of this low ball power limit. It would be best to fix the cooling if possible before adjusting the power limits.
TVB throttling happens when the CPU reaches approximately 70°C. You can disable this type of throttling by clearing the Thermal Velocity Boost box in the FIVR window. It would definitely be best to fix the cooling problem first before trying to disable TVB throttling.
Edit - PC Mag tested a Dell Precision 3551 with the higher end 10885H CPU. It was deliberately limited to 35W which reduced maximum performance.
The Precision 3551 ably fills the bottom slot in Dell's mobile workstation lineup, but a cost-no-object CPU choice made our test unit too expensive for its market segment.
www.pcmag.com