The BAMF website doesn't seem to discuss the possibility at all, and talks about the exams exclusively as Abschlussprüfungen (i.e. course completion tests). But it does appear to be possible to take the language test (Deutschtest für Zuwanderer) without attending an Integrationskurs. For example, this website for language tests at the Volkshochschule in Bavaria states that the exam is free for anybody attending the Integrationskurs, and gives prices (up to €160) for those who are not.
This school in Bonn states that:
Auch Externe - also Teilnehmende, die keinen Sprachkurs/Integrationskurs besucht haben - können diese Prüfung ablegen, in diesem Fall müssen sie die Prüfungsgebühr selbst übernehmen.
(free translation: "External candidates - that is, participants who have not attended a language or integration course - can also take this exam, in this case they must pay the exam fee themselves.")
I don't have any association with the schools above and can't vouch for their quality, they were just some of the first results I found on google. Note that the availability to anybody not participating in an Integrationskurs is dependent on the venue - I first checked the website for the VHS in Hamburg, where the test is explicitly not available to anybody other than course participants.
The same applies to the Leben in Deutschland test. The same school in Bonn states for their LiD tests:
Die vorherige Teilnahme am Orientierungskurs ist für Integrationskursteilnehmende verpflichtend. Interessierte, die extern nur am Test teilnehmen möchten, können dies gegen eine Gebühr von 25,- Euro und eine persönliche Anmeldung machen
(rough translation: Previous participation in the orientation class is mandatory for Integrationskurs participants. Interested people who wish to take only the test externally can do so after in-person registration for a fee of €25.)
Although as I said in my comment, I'd be very surprised if you as a Dutch citizen were to benefit to any meaningful extent from taking the Leben in Deutschland course or exam. Depending which regions you pick, the cultural/societal differences between Germany and the Netherlands are much smaller than those between Germany and other parts of Germany. If you want an idea of what it covers (and how simple the test is), the full library of possible questions is available online from the BAMF website.
As for the Einstufungstest, I don't see anything firm but I'd be very surprised if it's possible to take it without registering for the Integrationskurs - its only purpose is to determine which level of the Integrationskurs you should start at, there's no sense in offering it to people who aren't participating in the Integrationskurs. Note that it would only give a rough idea of your level anyway, and that any school that offering German language courses should be able to offer you a similar evaluation.