A full moon is the last of the moons four phases

You are making a statement, not asking a question. Can you phrase differently so you are asking a question of us, otherwise we don't know how to respond.

Tick

Is it true or false

I guess it is who wrote the phases.
New moon could be first phase, or it could be the last phase.
Chicken or the egg?

The full moon is neither the first nor last phase. The generally accepted phases are: new moon, 1st quarter, full moon, 3rd quarter (also called last quarter), then new moon again, etc.

The full moon is a phase of the moon experienced each month as it is on this night 19 March, it is neither first nor last. It has significance only because people have given it religious significance