It's usually a good hint that it really isn't a legitimate intrest case if they allow you to turn it off.
A legitimate intrest does not require an opt in (or an opt out). Consent does. If the page mixes those two up they're either clueless or trying to walk in the gray area and don't really understand(or don't want to understand) what either of those terms mean.
Legitimate Interest has a legal definition as a Legal Basis. It's a list of Purposes and Special Features that a Vendor declares to the IAB that they claim to need [0]. A User absoultely has the right to Object to Consent and Legitimate Interest.
Any CMP that does not allow you to opt-out is on shaky GDPR legal ground.
A legitimate intrest does not require an opt in (or an opt out). Consent does. If the page mixes those two up they're either clueless or trying to walk in the gray area and don't really understand(or don't want to understand) what either of those terms mean.