It is impossible to deny an individual dogma.
I think this is true. If one denies any singular dogma, s/he is also denying the dogma of infalible teaching authority of the Church. (which in itself seems more a schism, than a heresy.)
but it doesn’t necessarilly hold that all dogma is rejected.
newadvent.com. quotes Aquinas : **There are, therefore, two ways of deviating from Christianity: the one by refusing to believe in Christ Himself, which is the way of infidelity, common to Pagans and Jews; the other by restricting belief to certain points of Christ’s doctrine selected and fashioned at pleasure, which is the way of heretics. **
according to newadvent’s section on degrees of heresy :**a doctrinal proposition, without directly contradicting a received dogma, may yet involve logical consequences at variance with revealed truth. Such a proposition is not heretical, it is a propositio theologice erronea, that is, erroneous in theology. **
here’s the link: newadvent.org/cathen/07256b.htm
given the particulars of heresy i.e., distinctions, degrees etc., it seems entirely prudent to leave the label “heretic” to be used at the discretion of the Church.
In other words, “Kids, don’t try this at home.”