I'm running into the same problem with my '21 SEL.

Many places are not listing the '21 yet. From comparing the '20's and '21's side by side at the dealer, and knowing this is the last year for this generation, it is VERY safe to assume that if it fits a '19 and '20, it will fit a '21.

 

I realize this thread is two months old but thought I would add some info. I bought splash/mud guards for our 2021 SEL from buyhyundaipartsnow.com. They only listed up to 2020 so I called and they confirmed the parts were the same for 2021. The guards are Hyundai OEM in Hyundai parts boxes with QR codes for downloading instructions. The mud guards were about 1/2 the price shown on most Hyundai parts sites (including freight -approx $65). Shipping was 2-3 days.
Said all that to say this - check them out online, pick your accessories, compare pricing. call to confirm fit and you’ll probably buy from them.
2020 cargo tray - $84.75
2020 cross bars - $212.44
didn’t see all weather mats