Here I found something on it…
GIRM n. 43 describes the posture of the faithful during the Mass.
Stand from the entrance procession until after the Collect (the opening prayer).
Sit for the First Reading, Psalm, and Second Reading.
Stand for the Alleluia and the Gospel.
Sit for the homily.
Stand for the Creed and the Prayer of the Faithful.
Sit for the offertory.
Stand when the priest says “Pray, brethren…” and stay standing until after the “Holy, Holy, Holy”.
Kneel for the entire Eucharistic Prayer until after the “Amen”.
Stand from the “Amen” to after the “Lamb of God”.
(In some dioceses, you kneel after the “Lamb of God”.)
You may sit, stand, or kneel after you return to your seat after Communion.
You stand for the prayer after Communion until the end of Mass.