They will sell you a ticket with an unrealistic transfer time. I have seen 60 minute transfer windows. 2h20minutes is usually okay if you land on time. Before COVID, many of my international flights leaving from SEA were delayed by 30 to 90 minutes. We missed a transfer to Barcelona and had to wait four hours before we were "squeezed" on to a full flight from LHR to BCN. We had to run frantically through Schipoel to catch a transfer flight to Rome after a 30 minute delay. If you are flying economy on an international flight, and are seated midway to back of plane, it will take you a while to deplane. This will cut into your transfer time. We have learned to travel with carry-on luggage only. If you do miss your connection, be aware if the air-carrier is an EU carrier (we try to fly Air France, KLM, Luftansa....Not sure where British Air falls since Brexit) , there are very definite passenger protections and rights, including significant monetary compensation for delays over three hours. Under EU regulations, you may also be entitled to meal vouchers and other vouchers if you miss the connection due to delays with your originating flight. You really have to advocate with the agents at the airport if you have a delay or missed connection. They don't just provide the information on vouchers or compensations without a reminder.
Your plane is delayed if you reach your destination at least 3 hours later than the original scheduled time. You are entitled to compensation.
The compensation due in case of delay depends on the distance of the flight. It is:
250€ for flights up to 1500 kilometers,
400€ for flights between 1500 and 3500 km,
600€ beyond 3500 km, provided that you are at least 4 hours late (300 € for a delay between 3 and 4 hours).