The Bhutan visa allows you to remain in Bhutan for a maximum of 90 days from the date of entry. Extension of visa is available.
You can extend your visa while you are in Bhutan. Provided the extension is applied for before the original visa or permit expires. You can extend your stay via the online visa application portal, using the same log-in details that were used to process your original visa. The fees for processing your extension application, and daily SDF (USD 200 per people per night) for the duration of your extended stay, will be payable via the same portal. Read more about visa apply by 2023 updated Bhutan Visa Online Application Guide
Source : bhutan.travel (Sept. 2022)
Here is a Bhutan e-visa from our group for your reference:
Bhutan E-visa
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