Jose R. answered 04/30/21
Native experienced Spanish tutor from Spain with BA in Teaching.
I have been a Cervantes Institute examiner, which means I was one of the guys who evaluate students whom wanted to get a DELE diploma. I strongly suggest you to get the C1 level first. However, the gap between B2 and C1 is huge: to perform OK in B2 doesn't mean that you will get a good grade with C1 studying by yourself a little bit.
C2 level is for natives -and some of them will not perform ok with that test-. BUT, if you take a test based on the Common European Framework of Reference of Languages, C2 level test has questions about idioms of SPAIN, as DELE is a diploma endorsed by the Spanish government. If you are learning Spanish with a tutor who is not from Spain, you may find C2 (even C1) level extremely difficult, not because you don't know the grammar, but because the test set for using Spanish from Spain.
In English, you find the same issues: C1 level or any test based on the CEFRL is focused in English from UK, but if you take the TOEFL, it is made using American English.