Yes, you can choose to lay out your wishes. Many do, just like opt in or opt out organ donation. However, if you don't lay out your wishes, you will still end up buried or cremated or something similar without consent.

I'm not saying that's wrong. We can't just leave dead bodies where they lie. It also provides comfort to families to practice burial rites. My point is that technically you are still making decisions about what to do with somebodies body parts without consent, as they can no longer consent. Is there really a difference? If they care that much, will they just opt out?

I know some countries, they used to let you specify which organs, but then people opted out of eyes. So they removed the option and it was just donor or not. People still consented, without opting out of eyes. Is that better, or is that manipulating consent?

In most (all) European states you actually get a state mandated ID card, which has an expiration date. So the consent can be formed while filling out the formular to get a new ID.