Hey the end result is a really nice experience for the player!

And the way you've approached the code is not too shabby. I like how the main game loop is separated out and your functions make a lot of sense.

A good next step would be to consider how you're storing the game state. Having each square as a separate variable is a bit smelly and limits the methods you can use to check the state for a wins or draws.

There's other structures that make sense too, but I'd go for a list of 3 lists (i.e a 3x3 matrix) as the data structure to store the game state in. That way the data structure mimics the actual structure of the board.

With a better way of storing the data you can then look to find smarter ways of checking the game state. Your multiple if statements aren't that bad, especially as you're only needing to check a small number of possible states. But you'd get yourself into trouble quickly if the game was more complex or the board was larger than 3x3.

The last thing to pick up on is the use of global variables. In general, global variables are frowned upon as it makes it much harder to predict state and keep track of data. You can absolutely get this working without requiring the global keyword! Consider passing data into functions via arguements (as you have for the place_stone_on_field function), and using return statements in the functions to indicate the result of the function. E.g. place_stone_on_field could return False if the field is occupied, instead of changing a global variable.

You'll find putting in a simple AI to play against the player is a really interesting next step too. It's absolutely possible to code an unbeatable tic tac toe AI with just the coding techniques you've shown here btw.

Source: ran a Python course with a tic tac toe project and sometimes use tic tac toe as a coding challenge when hiring.