Can my website search flights for a trip with more than two cities, not just a simple return?

Yes, in most cases your website can handle a multi city trip, not only one way and return. The search form can be set up so your customer adds each leg of the journey separately, with its own departure city, arrival city and date, and the results come back as one itinerary with the full route and the total fare rather than as separate pieces your staff have to add up by hand.

When a multi city itinerary comes back from a single airline or a single source, it is normally booked as one reservation with one reference number, which makes it much easier to manage later if something changes. Your customer sees the whole route, the connection times and the baggage that applies, and pays once at checkout.

There are real limits and they come from the airlines and the suppliers, not from the booking screen. Different sources allow different numbers of legs, so a very long itinerary with many stops may not return results even though a three or four leg trip will. Low cost carriers often cannot be combined into one itinerary at all, so those legs end up as separate tickets with separate rules for changes and refunds. Some negotiated or special fares are only filed for one way and return journeys, so they may simply not appear on a complex route. What you can offer also depends on which sources are enabled for your account and on your plan.

The best next step is to try a few of the multi city routes your customers actually ask for and see what comes back, then tell us which combinations matter most to your business so we can check the sources available to you.