Yes, Planet Fitness does hire individuals who are 16 years old, although this can vary by location and specific state labor laws. Typically, while some positions may be available to those who are 16, certain roles, especially those involving more responsibility or requiring a higher level of maturity, may have age requirements of 18 or older.
If you're considering applying, it's a good idea to check the specific job postings for your local Planet Fitness. Job descriptions will often indicate the minimum age requirement for each position. Additionally, reaching out directly to your local gym can provide you with the most accurate information regarding their hiring practices and available job options for younger applicants.
Keep in mind that if hired, there may be restrictions on the hours you can work due to labor laws governing minors. This is worth considering when applying for jobs as a teenager.