For most package products, the departure and arrival dates cannot be changed with group air tickets.
Group tickets can be purchased at a lower price than individual tickets, but there are many restrictions on change or cancellation.
However, depending on the airline, you may be able to change your return by paying free or extra costs.
In that case, even if you are a country without a visa, the period of stay is limited depending on the purpose of entry,
so please contact the person in charge before departure for inquiries about return changes or extensions.