With no mic, the connector is most likely a standard TRS. Should work with your USB-C to 3.5mm adapter (dongle).I recently purchased a set of these inexpensive IEM's from Amazon along with a cheap JSAUX USB-C to 3.5mm adapter. The adapter description states "Not compatible with OMTP, TS and TRS microphone-only devices are not supported". OMTP looks to be a different connector type standard, but the IEM's I ordered don't have a microphone, so hopefully OK (TRS maybe?). I also ordered a set of earbuds (JBL Endurance Run 2). These do have a microphone (probably TRRS). Presumably the USB-C adapter itself is also TRRS, but will it work with both pairs of headphones?
With a mic. there are two main standards: OMTP and CTIA. They are both TRSS, but the pinout differs:
Some adapters/dongles are compatible with both (they have a detection feature).
Your adapter is only CTIA-compatible.
I don’t know about your JBL earbud. Worse case, it may not work, or one side won’t work.