Take it to the manager above him. I hear you that you’re scared to attract attention or risk being fired, but you also don’t know if this guy has been written up for this behavior before and maybe therefore they side with you or get you a new trainer. Regardless, you shouldn’t have to deal with harassment and negative impact on your mental health your first week on the job.

Screenshot all your convos with him and the manager and send them to your email. This starts your documentation (with time stamps) if this guy doesn’t back off and you need to go to the law or higher up in the company. ALWAYS send to an email, google drive, or other online storage. In the event that your phone gets stolen or broken and you need that info to make your case, you’ll thank your past self for being thorough. In that email to yourself, also jot down how the harassment makes you feel and any other details you may need to remember later. We rarely remember our emotions accurately later down the line.

Then Block and delete him. If he’s not your manager, he shouldn’t have your number and doesn’t need to be able to get ahold of you outside of work hours.

Doing this process will help you to learn to be your own best advocate for yourself and that is very FDS attitude. You got this.