Asking for player name and age using OOP
The methods in this class are not really Player methods. They are a combination of game flow, user input and value verification methods.   I'd organize it more like this.
class Game:
  def __init__(self):
    io.show(&quot;If ready, let's begin&quot;)
    name = self.get_valid_name()
    age = self.get_valid_age()
    self.player = Player(name, age)
    io.show(&quot;Hello {}, prepare for battle&quot;.format(self.player.get_name()))

The Game object owns the flow of control.  The I/O is encapsulated in an object which can be a simple stdio wrapper for now, but may eventually include non-blocking input or html output or whatever - don't tie the game logic to the display method.  The Player object contains player state.
The get_valid_x methods can basically be what you have now. If you are using that pattern over and over, you could get fancy and write a parameterized validator:
def get_valid_input(prompt, validation_func):
  while True:
    input = io.prompt(prompt)
    guidance = validation_func(input)
    if not guidance:
      return input
    io.show(guidance)

def validate_name(str):
  if not str.istitle():
    return &quot;Please enter name beginning with capital Letter&quot; 
  return None

 ...
 
 name = get_valid_input(&quot;What is your name?&quot;, validate_name)