The DS3232 works at 3.3V and at 5V.
The BMP280 works only at 3.3V.
Some sensor modules have a voltage regulator, some modules also have level shifters for I2C.
The basic Arduino boards are 5V Arduino boards.
What I am trying to say is this: Don't connect the BMP280 chip itself to 5V and when you connect a 5V I2C bus directly to the BMP280 then the BMP280 can get damaged.