Here are some steps you can take to try and resolve the issue.
1. Check your email provider's settings: Ensure that you have properly configured the spam filter settings for your email provider.
2. Verify your email provider's blocking rules: Ensure that blocked senders are indeed being sent to the trash or junk folder, rather than being returned to your inbox.
3. Update your email filters: Create custom filters to catch specific keywords, phrases, or sender addresses that are commonly associated with spam emails. This can help automatically redirect unwanted emails to your junk or trash folder.
4. Report spam: Apple has a button that you can press to send the email to “Junk” and it should have all future emails from that address also go to junk.
5. Avoid sharing your email address publicly: Ensure that you are cautious when sharing your email address online, as this can lead to an increase in spam emails. Consider using iCloud+ to use the Hide my Email feature. You can sign up for as little as $0.99/Month USD, and it is worth it.
6. Use a third-party spam filter: If Apples’ spam filtering isn't sufficient, consider using a third-party spam filter.
7. Consider changing your email address: If all else fails and you continue to receive an excessive amount of spam, it may be worth considering changing your email address and starting with a clean slate.