Is myself pronoun

No, the pronoun 'themselves' is a reflexive pronoun, a Word that 'reflects back' to its antecedent.

The reflexive pronouns are: myself, yourself, himself, herself, itself, ourselves, yourselves, themselves.

The reflexive pronouns also function as intensive pronouns, a Word used to emphasize its antecedent.

A personal pronoun is a Word that takes the place of a noun for a specific person or thing.

The personal pronouns are: I, you, we, he, she, it, me, us, him, her, they, them.

Example uses:

The Jacksons enjoyed themselves at the picnic. (reflexive pronoun)

The Jacksons painted their house themselves. (intensive pronoun)

The Jacksons came for a visit and theybrought the baby with them. (personal pronouns)