You're not going to get DLSS3 with an RTX 3000 card. I'm afraid that nVidia decided to only allow people with RTX 4000 cards to use DLSS3 so you're out of luck there no matter which card you choose.
As for the video encoder... well, yeah, I guess it's "better" but it's not like the H.264/265 encoder on the Radeons doesn't work (I use it quite often with very good results).
Now, MrN1ce9uy showed you that the RTX 3060 is going to cost $530 for an RGB model. That's a complete rip-off (as he says, who would want nVidia these days?) which is only par for the course for GeForce cards. To give you an idea of just how bad a price that is, you can get an RX 6800 XT that's suitable for a vertical mount for only $10 more:
ASRock RX 6800 XT Phantom Gaming D 16GB - $540
The performance difference between the cards is absolutely ridiculous because the RX 6800 XT is a colossal
84% faster. That's right, it's close to double! Do you really think that having a somewhat better video encoder is really worth sacrificing an extra 84% of gaming performance?
(Here's a hint: Not a chance in hell)
I can personally attest to just how amazing the RX 6800 XT is because I own one. There's no question in my mind that I made the right choice because I'll never have to worry about how much VRAM I have and I'll be able to play games at 1440p or higher for the next 3-5 years and I'll probably be able to make 1080p work for another 5 years after that. If you're willing to pay $530 for an RTX 3060 12GB, then paying $540 for an RX 6800 XT 16GB should be a no-brainer.
The only drawback to it is that you'll need a new PSU because TechPowerUp recommends a
700W PSU for it. Even if that disqualifies it though, it paints a pretty good picture of how GeForce cards are just not worth what they currently cost.
I just hate seeing people get fleeced.