In film and video, the director just sets up the shot he wants his audience to see. On stage, focus or the audience's eye, must be manipulated with blocking (positioning) and movement. The audience must not be confused about where to look. You tell them where to look...

Always be mindful that your audience, that farthest row back, needs to hear you, even though your scene partner may be right next to you. https://youtu.be/3NrhghEbxYQ