void PlayAnimation(AnimancerComponent animancer, AnimationClip clip)
{
    var state = animancer.Play(clip);
    state.Time = ...
    state.NormalizedTime = ...
    state.Speed = ...
    state.OnEnd = ... 
string s = "test"
}

Speed and time control are demonstrated in the Fine Control examples.

Those properties are not included as parameters in the Play methods because they already have multiple overloads with several default values and a call like Play(clip, 0.25f, 1, 0.5f, 0.5f) would not be particularly clear about what each value does without close examination. But if you really wanted to, you could implement them using extension methods:

public static class AnimancerExtensions
{
    public static AnimancerState Play(this AnimancerComponent animancer, AnimationClip clip, int layer, float time, float speed, System.Action onEnd)
    {
        var state = animancer.Play(clip, layer);
        state.Time = time;
        state.Speed = speed;
        state.OnEnd = onEnd;
        return state;
    }
}