@Shuvam ******

Non-B is usually applied when the applicant is in overseas for work and business purposes , but under the circumstances that u can convert to Non B visa if you already have a valid work permit from previous Non B visa but exit Thailand to get a travel visa, then when u reenter, u can convert your travel visa to a Non-B visa, but it is called “convert “ rather than “apply”.

U can interview with your potential employer on a tourist visa, but to work, u must exit Thailand and apply for Non-B

there r agency does this for money, let u use other company's qualifications for a cost, but it is risky for both the "employer" and "employee".