Can I paint over tile backsplash or put Sheets of plastic tile on it

https://www.countryliving.com/remodeling-renovation/how-to/a300/paint-tiled-backsplash/

You can paint it with the proper prep for sure, but sheets of plastic tile probably wouldn't adhere well, or have a smooth look over the grout. There are tile stickers or decals available that are individual, or at least smaller that are made for that purpose. Here's a link to give you ideas. Amazon has some also. https://stickpretty.com/collections/tile-decals

As long as you clean and degrease your existing backsplash, it should be fine to do a peel and stick option. Just bear in mind that higher temps near your oven/stove could affect tile adherence. I would advise against painting the tile unless you were painting the tiles individually and still maintaining grout lines.

You can paint tile, but as explained by Gentry, there are some issues. If you do paint them, you can always repaint the grout lines. Just make sure to seal everything with several coats. If you go with the stick on tiles, make sure there aren't any raised areas on the tile, they won't stick properly.

Rustoleum Tub and Tile Paint kit. Peel and Stick tile need a smooth flat surface to adhere.

I painted my tile backsplash about a year ago and still looks good. One of the really key points is to make sure you degrease well and then allow to dry before putting on a good primer. Janet's link above is great and is pretty much what my Benjamin Moore dealer told me. Good Luck!

You could do either, or apply Tile covers instead?