I've found that culture is king in terms of governing what's shipped. From day 1 new hires are looking at what their peers are doing, and more importantly what's being tolerated by the manager and the rest of the team.

As an uninvited specific action recommendation: I've made it a habit to look through PR's (merged and unmerged) regularly. I point out opportunities for improvement, and more importantly I call out excellent solutions. The excellence can be in the form of elegance or just hard graft finding a bug. It's a small action that's additive and doesn't interrupt work. But it does wonders at setting the tone.

One thing I've found very hard indeed is if the team you manage is surrounded by peers that "don't give a fuck if what they do works or is of merchantable quality". However, if you reinforce your culture of excellence it becomes resilient to it ... and then the tricky thing becomes avoiding arrogance within the team.