Link in spam email

Probably nothing immediately bad, but I’d not make a habit of engaging with spam. (This PDF access will flag your address as being valid, and will flag your willingness to engage with and to open spam, which makes your email address far more valuable for resale and for yet more spam.)

PDFs can be malware and can contain executable code, though that type of malware is not usually a problem on iOS and iPadOS, given the limits of the Preview app. Other PDF viewers might or can have larger risks here.

PDF malware details: https://arxiv.org/pdf/2107.12873

Similar to PDF malware, Microsoft 365 (Office) documents can contain macro malware, as well. Those can be more of a problem, as Microsoft 365 can execute those macros. Best to keep macros disabled.

On macOS, having a rule that either blocks messages with problematic attachments from unknown senders, or that strips the attachments from unknown senders, can sometimes be helpful. This depending on your particular situation.

Forensics info for problem PDFs: https://intezer.com/blog/incident-response/analyze-malicious-pdf-files/

You did not lose any personal information by opening a PDF. The only thing that happened is that the spammers know you clicked a link in their email and are susceptible to future phishing attempts. You can expect more.

Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support