I want to develop a game on multiple devices such as PC, Android or IOS. Want it to be in 1080p, but that means a massive scale down for the smartphones.

I know how to do that, just render everything on a 1080p rendertarget and then render it on the screen smaller.

But what should I do so that the scalling down doesn't look bad and blury? I can't do it vector based or anything because the sprites simply need a specific size. Should I make the sprites power of two size to get some nice mipmapping? And which other settings can I do?

Or should I rather go with a lower resolution but then having a little bit worse look PC version? The performance seems not to be a problem for me, so would be sad not using 1080p because of other problems.