Thank you for your answer.I went to Halfords, but they didn't have universal coolant. Instead, I bought the one recommended by Halfords, which is the OAT pink coolant.
I just came back, and I am currently waiting for the engine to cool down. It appears that the coolant tank is empty, and I have no idea what color was used by the previous owner.
Could there be any potential damage if it turns out that the previous owner used a different color coolant?"