My sprites don't fit in a single 4K Sprite Atlas. What happens with the remaining unpacked sprites that are added to a Sprite Atlas?

Question

https://i.gyazo.com/3329293af0b92bf6ec443d8fb8b5d113.mp4

I tried to add a whole frame by frame animation clip to a Sprite Atlas but I don't want to ecceed 4K resolution. Do you think it automatically packs the remaining unpacked sprites in extra Atlasses that it generates?

We have a lot of animations with a high resolution target and I was looking into using Unity's Sprite Atlas to automatically pack the frames inside Unity instead of using an external tool.

https://i.gyazo.com/3329293af0b92bf6ec443d8fb8b5d113.mp4

The preview suggets there are multiple results but only the first result is shown there.