How much optical zoom does a camera usually need to take pictures during a trip?

Of course, it's better to enlarge the travel photos. Personally recommend 4 times, because the imaging above 4 times is poor, and below 4 times is inconvenient. There must be a wide angle, which is most commonly used to shoot landscapes, not telephoto ends.

Of course, if you use a fixed focus machine, such as GR-D, which is equivalent to 28mm, you will also achieve very good results. The key is the photographer, not the machine.