Here is a Sermon Guide for Extraordinary Form (EF) Masses based on the Summa Theologica of Saint Thomas Aquinas. First is this Sunday.
Of course, the Philippians (chapter 4) Epistle can be preached for Ordinary Form Masses too, since the Gaudete entrance antiphon comes from it. It is also the Second Reading of Year C. The Gospel is used in Year B.
The reference I give is to the first question dealing with each topic, which might go on, beyond the question cited, to succeeding question(s).
Next I give the preceding Sundays of Advent. Note also that the EF Gospel for the Second Sunday is the Ordinary Form Gospel this Sunday (Year A).
3rd Sunday of Advent
EPISTLE (Philipp. 4:4-7)
"Rejoice"
Joy II-II Q.28
Sins opposed to II-II Q.35
"Let you modesty" II-II Q.160
Kinds of modesty II-II Q.161
"The Lord is nigh"
How god is present in things I Q.8, a.2
Specially present in man I Q.8, a.3
Specially present in the saints I Q.,8, a.3
"In everything by prayer"
Prayer II-II Q.83
"And the peace of God"
Peace II-II Q.29
GOSPEL (John 1:19-28)
"And he confessed and did not deny"
Humility II-II Q.161
Grades of II-II Q.161
Virtue of truth II-II Q.109
Lying II-II Q.110
Baptism of John III Q.38
Sin of lying II-II Q.110, a. 3
Sacrament of Baptism III Q.68
Law and grace I-II Q.109
"Nor the Prophet"
Prophesy II-II Q.171
"Whose shoe I am not worthy," etc.
Perfection of God I Q.4
Can the human qualities in Christ be said of Christ as God III Q.16, a.4
2nd Sunday of Advent
EPISTLE (St. Paul Rom. 15:4-13)
"What things soever were written"
Necessity of Scripture, etc.
Truth of Scripture II-II Q.110, a.1; a.3
"Be of one mind to another"
Avoiding discord II-II Q.35
"Jesus Christ was the minister of circumcision"
Christ preaching to Jews and Gentiles III Q.42, a.1
"Gentiles are to glorify God for His mercy"
Conversion of Jews due to justice and truth
Conversion of Gentiles to God's mercy I Q.21, a.4, ad.2
GOSPEL (Matt. 11:2-10)
"Art Thou He who art to come"
Did John doubt Christ was the Messias? II-II Q.2, a.7, ad.2
"Blessed is he that shall not be scandalized in Me"
Faith II-II Q.1
and charity II-II Q.6, a.2
Christ II-II Q.6, a.1
Explicit belief in Christ necessary? II-II Q.2, a.7
"A man clothed in soft garments"
Virtue or vice of eternal adornment II-II Q.169, a.1
Use of expensive clothing II-II Q.169, a.1, ad.2
Religious (mendicants) and use of shabby garments II-II Q.169
Women, and expensive clothes, and covering
head in church II-II Q.169, a.2
use of rouge, powder, etc. II-II Q.169, a.2, ad.2
use of men's clothes II-II Q.169, a.2, ad.3
Men using women's clothes
External worship. See Gospel for 1st Sunday after Octave of Pentecost
"And more than a prophet"
Was John a greater prophet than Moses? II-II Q.174, a.4, ad.3
How John was more than a prophet III Q.38, a.1, ad.1
"Who shall prepare Thy way before Thee"
How John prepared the way of the Lord III Q.38, a.1; a.2, ad.2
1st Sunday of Advent
EPISTLE (St. Paul Rom. 13:11-14)
"When we believe," etc.
Faith II-II Q.1
necessary for salvation II-II Q.1 a.3
articles of II-II Q.1, a.6
articles enumerated II-II Q.1, a.6
symbol of II-II Q.1, a.9
Gospel and defined truths II-II Q.1, a.9
"The night is passed"
Old and New Law I-II Q.107
"Not in rioting and drunkenness"
Gluttony II-II Q.148
Drunkenness II-II Q.150
"Not in chambering and impurities"
Chastity II-II Q.151
Lust II-II Q.153
"Not in contention and envy"
Discord II-II Q.37
Contention II-II Q.38
Envy II-II Q.36
"Put ye on the Lord Jesus Christ"
Putting on Christ III Q.69, a.9, ad.1
GOSPEL (Luke 21:25-33)
"There shall be signs in the sun" Suppl. Q.73
"Sun, moon and stars not giving light" Suppl. Q.83, a.2
"The powers of the heavens shall be moved"
How the powers of the heavens will be moved at coming of Our Lord Supp. Q.73, a.3
"Seeing the Son of Man coming"
The general judgment Suppl. Q.88; 89; 90
Judiciary power of Christ
special to Christ
extent of
"With great power and majesty"
Do the condemned witnessing this power recognize Christ as God? Suppl. Q.90, a.3
See also Gospel for All Souls' Day