It is certainly in my opinion an ineffabilist position if by that you mean a quietist position.
The buddha explicitly states, dozens if not hundreds of times, in multiple contexts, that some things should not be said of (many, most? all? at least several lists of very broad) phenomena, see here for a survey:
The buddha explicitly states that some things should be said, of most of these same phenomena, see here:
https://discourse.suttacentral.net/t/the-great-escape/
I think this is a Theravada position and I think it is not supported by the weight of evidence in the EBT.
The aggregates are a later scholastic adaptation of the teachings that spread in the late pre-sectarian period and must threrefor be compatible with the abyakata/nisaranca framework which preceded it. for a lengthy textual examination of the basic evidence see here:
https://discourse.suttacentral.net/t/are-khandhas-early-or-late-ebt/
At SN33.1 for example we have:
“What is the cause, Master Gotama, what is the reason why these various misconceptions arise in the world? That is:
“ko nu kho, bho gotama, hetu, ko paccayo, yānimāni anekavihitāni diṭṭhigatāni loke uppajjanti—the cosmos is eternal, or not eternal, or finite, or infinite; the soul and the body are the same thing, or they are different things; after death, a Realized One exists, or doesn’t exist, or both exists and doesn’t exist, or neither exists nor doesn’t exist.”
sassato lokoti vā, asassato lokoti vā, antavā lokoti vā, anantavā lokoti vā, taṁ jīvaṁ taṁ sarīranti vā, aññaṁ jīvaṁ aññaṁ sarīranti vā, hoti tathāgato paraṁ maraṇāti vā, na hoti tathāgato paraṁ maraṇāti vā, hoti ca na ca hoti tathāgato paraṁ maraṇāti vā, neva hoti na na hoti tathāgato paraṁ maraṇāti vā”ti?“Vaccha, it is because of not knowing form, its origin, its cessation, and the practice that leads to its cessation
“Rūpe kho, vaccha, aññāṇā, rūpasamudaye aññāṇā, rūpanirodhe aññāṇā, rūpanirodhagāminiyā paṭipadāya aññāṇā; that these various misconceptions arise in the world. evamimāni anekavihitāni diṭṭhigatāni loke uppajjanti— sassato lokoti vā …pe… neva hoti na na hoti tathāgato paraṁ maraṇāti vāti. This is the cause, this is the reason.” Ayaṁ kho, vaccha, hetu, ayaṁ paccayo, yānimāni anekavihitāni diṭṭhigatāni loke uppajjanti— sassato lokoti vā, asassato lokoti vā …pe… neva hoti na na hoti tathāgato paraṁ maraṇāti vā”ti.
The teaching repeats itself for the other five aggregates of course, but the central point made is clear, to fully know an aggregate is to fully know that it doesn’t exist, not exist both or neither, rather it has its conditional beginning, it’s conditional end, it’s appeal, it’s repulsion, and it’s trancendence/escape.
This is the teaching of the buddha, the complete statement of which (apart from a few dangling technicalities) can be found at DN1 and DN2.
The aggregates are no more or less real than the self or anything else we deal with in this life.