The system has rtx 2060 super.
Really need the full pc spec, everything needs to be considered. Also the resolution and Hz. The i9 9900 is more powerful for gaming but there is a lot more to consider. If you don’t have a motherboard already the i7 10700 would be a better choice. If you already have a motherboard does it have VRM’s good enough to properly run the 9900, just because a cpu might be supported by a motherboard does not mean it is a good choice due to the very high power requirements. Also do you have sufficient cooling for such a hot cpu.
Other factors are it’s highly unlikely that an RTX 2060 is powerful enough to utilise the extra performance of a 9900 over the 9700f. Maybe if running a very low resolution. Does an extra few FPS even matter if the monitor is not high enough Hz to benefit or too high resolution for a 2060 to push high fps.
Generally speaking a 2060 and 9900 is unbalanced. A better balance would be a 2070/2070S and 9700 or 10600.
The 9900 is only better if you are stuck on that cpu socket and the other hardware will allow you to fully utilise the extra performance. Is the 9900 worth the extra cost is a different question, paired with a 2060 I would say no.