sql server – MS SQL “migration” to older version – problem with Attach

On SQL 2019 I try to change compability level to 2008 (to be sure that I will be able to attach on older version, at least I was in hope this will be possible).

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I detach this db.

When I try to attach on destination SQL I still get
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As so far I found few related topics like this following:
Restore DB to older version

But there are talks about Restoring backup, but I ask about Detach/Attach and compability level.

So Here are my questions:

Question 1: Is there any way to attach newest mdb file on older SQL server ?

if NO

Question 2: What for is feature “Compatibility level” ?