What is the ruling on a sick person, who intended to break their fast, taking medicine and having intercourse with their wife during daylight hours in Ramadan before traveling? And is expiation obligatory for someone who did that and then traveled?

If you are ill with an illness that permits you to break your fast in Ramadan (definition), then it is permissible for you to intend to break your fast, take medication, and engage in marital intimacy (if your wife is also not fasting for a permissible reason). In this case, you only owe a make-up fast.

However, if you are healthy or have a mild illness that does not permit breaking the fast, then it is not permissible for you to intend to break your fast, take medication, or engage in intimacy. If you engage in intimacy after invalidating your fast with the intention of breaking it and taking medicine, then the severe expiation becomes obligatory upon you (freeing a slave; if unable, then fasting for two consecutive months; if unable, then feeding sixty needy persons).

The intention to travel does not justify breaking the fast, taking medicine, or engaging in intimacy before actually commencing the journey, and actual travel does not waive the expiation that became obligatory before it. The expiation is also obligatory upon the wife, according to some scholars, if she was not coerced or did not have a valid excuse. In such a case, both of you must make up that day.