WHO CAN PARTAKE?
The relevant scriptures say that those who partake of the Lord's Supper-Table should know and understand what it is they are doing.
This is a feast of thanksgiving and worshipful gratefulness. It involves a self-examination (personal spiritual check-up) before partaking of the bread and the fruit of the vine in the manner that the Lord initiated.
Adults who have received Christ, who involve themselves in His word, have been immersed in water and have foundational understandings should qualify to partake. (For more see Your Kingdom Foundation on the Menu).
But for those who desire to be first-timers partakers some preparation is likely to be required.
Who Can Partake? Outside of this Kingdom Inheritance context answers vary according to the doctrines and criteria of a denomination.
They range from not keeping the Lord's Supper at all to having "Communion", "Eucharist", "Mass" or a version of it. In addition, some have no criteria at all and include children as part of a loosely-defined ceremony.
These are carried out in sincerity. Nevertheless, they seem not to be done "in truth".
“... the hour is coming, and now is, when the true worshipers will worship the Father in spirit and truth; for the Father is seeking such to worship Him.
“God is Spirit, and those who worship Him must worship in spirit and truth,” John 4'23-24.
All that said, in order to honour the Lord's Feast according to His will, it is necessary for a Believer to be of age.
Being of age is when a Believer is developed enough to possesses the New Covenant Kingdom understandings that are necessary before participating in the Lord's Supper (and Immersion in Water too).