Yes and no. I agree because EQ is an easy way to get more bass, but it is an very unreliable and inconsistent way to get more bass.Pssssst, If you like deeeep bass, use a little bit of eq
Some DAPs do support it, some only very limited, some dont. Some not with external USB and so on.
Also, if the IEM doesn't have the hardware to back it up, you risk distortion.
But if you have an good EQ, an IEM with the hardware that does not fall apart when using EQ, that is actually the cheapest and best way to get exactly the sound you want.