On the application they ask you how you plan to enter the country and where.
- Are you bound to coming in the same exact what way?
- What if I decide not to fly or arrive at a different city, am I obliged to somehow update my itinerary?
TLDR : Answer Summary
When applying for a visa to Thailand, you are not strictly required to adhere to the exact travel itinerary you provide. It is common for plans to change, and as one commenter noted, you can simply submit a proposed itinerary. However, keep in mind that some embassies may consider the date listed on your application when processing your visa, potentially putting your application on Pending Approval if the date is far in the future.