I’m not sure exactly what you’re asking here: are you asking about editing the musical content itself, or the formatting?
If the former, then you can prevent e.g. doubling a note value causing everything else to shift along by the difference in the note duration by working with Insert mode switched off, though of course this means that if you make a note longer, you will overwrite the notes that were previously in the rhythmic range now covered by the note’s longer duration.
If the latter, then eventually we do of course expect to have features to lock the formatting of the music such that you can prevent Dorico from reflowing bars onto other systems, though I would encourage you not to lock things down too early in the process of putting your score together. A good part of Dorico’s power comes from its ability to make changes on your behalf as your music changes.