If you want a coordinator with experience and who could be a good playcaller then look at Darrell Bevell. He has 15 years of experience and was offensive coordinator for the Minnesota Vikings, Seattle Seahawks, Detroit Lions, and Jacksonville Jaguars. In that time, he also served as interim head coach for the Lions and Jaguars.
In 2013, Bevell interviewed for the Chicago Bears head coaching job that eventually went to Marc Trestman. We saw what happened with Trestman. Meanwhile, Bevell stayed with the Seahawks and won a Super Bowl.
Bevell is currently the Miami Dolphins' quarterbacks coach/passing game coordinator. He works well with Tua Tagovailoa. The Dolphins have the second-best scoring offense and the best passing offense in the NFL.
Additionally, he worked with a number of different types of quarterbacks like Brett Favre, Russell Wilson, Matthew Stafford, Trevor Lawrence, and Tua. He has seen them all and he is still only 54 years old.
Bevell would be good working with Fields or handling a rookie quarterback.