Be careful. 2020 got a redesign of the footwell fuse box. I got this for my 2020. See all of their items for alternative colors.
2020 Toyota 4Runner Black Fuse Box Cover with Side Slots | eBay
I don't know about 2021, but I bet it's the same as 2020. Then again
Heads up, I had to get a hair dryer and use it to reshape the clips and tried bending the whole thing down the center a bit. After doing that, it's been solid since August. The only special tool I needed was the hair dryer. You can use whatever crap you've got lying around to create a little "bridge" for the whole unit and whatever weight you can find to apply into the center of it to try to get the curve out of it. Hit it with the hair dryer while you're doing that but not too much to make the plastic too pliable and you should be fine. Same thing with the clips. I recommend a hair dryer and not a heat gun especially for the clips because you don't want it getting too pliable or just turning into goop, and if it's too hot you won't be able to reshape it safely with your fingers.