Set the bar high/ low
Set the bar high/ low (English) — To have or introduce a standard of behavior, or actions that is of a 'high' expectations and requirements. To set a 'low' standard is to underestimate, and not challenge people. When you know the bar is set high in a group you behave and are mannerly and thorough in everything you do.
The literal reference is to the bar used in high jumping (a sport, or event). The higher the bar, the more difficulty.