There is no way to know if a campaign email landed in the spam folder or the inbox. In order to confirm that status, the recipient's account has to be checked.
Keeping in mind the security and privacy of the recipient's address, and for technical reasons, there can't be a system that can accurately tell which email landed in the lead's inbox and which landed in their spam folder.
Certain tools can help you to get a detailed delivery report. They provide a list of their leads to which you can send emails to. Based on how many of those emails land in their inboxes, they generate a delivery report.
You can test with these tools:
Mail Tester — Overall deliverability score (Mailbox health + copy quality)
Spam Checker — Checking the content of the sequence/campaign.
So in a nutshell, ultimately deliverability of the email accounts can only be speculated based on the following factors.
Your own domain's reputation and how old it is.
Reputation of email service provider's IP.
Whether you are using SPF, DKIM AND DMARC.
If there are any links/images that you have included — even the open tracking pixels can have an impact.
More details can be seen clicking on Forge Deliverability Master Checklist.