It depends tbh.
More often than not, the answer is usually no: Since by the objective term, an Incel is someone who desires a relationship which implies that they even tried.
However, if someone is genuinely that unappealing looks-wise or has been treated so badly by others(especially foids) due to their looks, height, autism, etc. than ofc. they still are clearly Incel, and basically trucel. Some users he write that strangers in public recoil at them & give them glares, and we also have a few who are under 5'6 which is turbomanlet tier.
So genuinely no, most who haven't asked a foid out are arguably non-incel: However in cases of trucels, turbomanlets, giga-autists or schizos, etc. I'd say they have a valid reason to have not done so.