Yes it is because it is part of a verb
it is verb
Verb have is the helping verb sold is the action verb
"Do" is a verb when used in a question as a helping verb helping to form the interrogative structure.
In this case, will is an auxiliary verb, which is the grammatical term for a 'helping' verb.
'helping verb - or auxiliary verb
It's a verb, a compound verb made from the infinitive stem "be" and the auxiliary "can". In addition, "Can be" can be a helping verb phrase, e.g. "Tom can be helping the younger kids". Can be is helping the verb helping.
"Has started" is a verb phrase. "Has" is the helping verb (auxiliary verb) and "started" is the main verb.
The word been is a verb. It is the past participle of the verb to be.
Sold is a verb. It's the past tense of sell.
Is gaining is a verb, consisting of a helping verb is plus a present participle gaining.
Does is always a verb.When does is next to have you can call it an auxiliary verb or helping verb.
Be is a verb. It's an auxiliary verb in "will be performed".