Yes, you can extend the duration of your Thailand work visa once you switch from a 90-day entry visa to a full-time one-year visa after obtaining a work permit. You must, however, fulfil specific criteria to apply for a Thailand work visa extension, which includes getting a job from a registered Thai company that meets the employment ratio and financial requirements. To successfully extend your work visa application, you must also submit documents, including a valid work permit, passport, visa extension form, and sufficient funds.