We've had threads like this before. Unfortunately, no there is no way to tell what your dope is cut with, be it fent or anything else, without a lab or some kind of chemical test.
I'm going to close this as there really is nothing else to say, as we've already had threads like this, and there is no point in speculating on ways to eyeball or gauge whether there is fent in your dope without an actual chemical test.
PM me with any questions.
Thanks.