You mentioned the importance of posterior pelvic tilt when doing the dead bug series, leg lowering, etc.
Should I also keep posterior pelvic tilt when doing front planks?
The goal isn’t so much posterior pelvic tilt for the sake of posterior pelvic tilt. Most people need this in these particular exercises because they have such a large degree of anterior pelvic tilt.
Perform all these exercises with the end-goal in mind: A neutral pelvic tilt. Once you’ve achieved this statically, the goal is to have the core stability to maintain this optimal alignment when lifting (e.g. squatting, deadlifting, etc.). This will allow you to engage the glutes in the bottom of these exercises. Better glute activation/control/strength will lead to more balanced and efficient lifting, as well as improved performance.