How to do a specific scene changing effect?

This is a cut scene I took from another Unity game.

Link of the gif: SceneChanging on Make a GIF

I’m wondering how to make a scene changing effect like that?

I tried to draw a complete black sprite with a little transparent hole in the center, then make it hundred times bigger through time. However, this will make the center hole looking all spiky and jaggy.

Does anyone have any other ideas?

You can use your current method but with a little tweak.

Since you are upscaling a sprite it gets pixelated and looks all spikey and jaggy.

You should rather use a sprite with bigger size and then move from a smaller size to its regular size because downscaling a sprite is always better than upscaling it.