Manual:

//Define:
public static class ModSounds
{
    public static readonly ModSound Sound = new("res://Mod/audio/sound.ogg");
}

//Play:
ModSounds.Sound.Play(); //See optional params of play methods.

Using AutoModAudio:

//Define:
public class MainFile
{
    public const string ModId = "Mod";
    
    public static readonly AutoModAudio Audio = new AutoModAudio($"res://{ModId}/audio");


//Play:
MainFile.Audio.PlaySfx("sound.ogg");

BaseLib will also play sounds when a resource path is provided to the basegame FMOD event player.

    //In a character
    public override string CharacterTransitionSfx => "res://Mod/audio/sound.ogg";
    public override string CharacterSelectSfx => "res://Mod/audio/sound.ogg";

Playing sounds directly without defining them first:

ModAudio.PlaySound("res://Mod/audio/sound.ogg");