I would recommend Posting guidelines in #Help channel to post better organised info about issue, in this case code.
To your topic :
1.) you can extend your player in your script and get reference to it as class, and add the node into group
class_name Player
extends CharacterBody2D
Other script
var player: Player
func _ready():
player = get_tree().get_first_node_in_group("player") as Player
2.)use export variable to get reference to node.
@export var player: Player
Assign corresponding player node in inspector on the right side.
3.) last resort use Singleton/Autoload.