i'm using ionic 5, i'm trying to cover the image background and make it not-repeat, so in ionic 5 i dont know if its possible
usualy i do like this:

background-image: url(assets/BGpaper-01.png);
background-repeat: no-repeat;
background-size: cover;

Using ionic they have custom css property for ionic components, for example:

ion-action-sheet, the background must be like this:

--background: url(assets/BGpaper-01.png);

for no-repeat and cover i try this:

ion-action-sheet {
--background: url(assets/BGpaper-01.png) no-repeat center center / cover;
}

• but seems not work for me*