We should be remember that the book of Revelation is prophesy (chap 1 v.3). John, in his calling as a prophet was commanded to:
Write the things which thou hast seen, and the things which are, and the things which shall be hereafter; Rev 1:19 (KJV).
Chapter 1 is the vision of the Son of Man which John had seen.
Chapters 2 and 3 refers to the things that are: ie the churches. Not just the seven mentioned (see ch22 v.16), although they prophetically typify the churches which have existed and will exist in the church age until the church is taken away.
Chapter 4 to the end describe the things which shall be hereafter ie after the true church has been taken to heaven and judgement begins.
Come up hither, and I will shew thee things which must be hereafter. Rev 4:1 (KJV)
Each of the addresses to the 7 churches include four statements from the Lord
1 The character of Christ which is always adapted to the state of the particular church.
2 In each church we see the special character of the trials of the faithful.
3 A special promise is given to sustain the faith of those under the trial. So there is grace to suit their special circumstances.
4 Looking forward to the time of fullest blessing, we see the portion given “to him that overcometh,” when Christ has taken the saints to Himself.
Just looking at the first, to the Ephesus,
“He that holdeth the seven stars in his right hand, who walketh in the midst of the seven golden candlesticks”—
The 7 stars in His right hand were seen by John back in chapter 1 v16, and in chap1 v 13, He is seen walking among the 7 candlesticks. Rev 1 v20 explains what these things were. "The mystery of the seven stars which thou sawest in my right hand, and the seven golden candlesticks. The seven stars are the angels of the seven churches: and the seven candlesticks which thou sawest are the seven churches".
This shows the character of Christ revealed in exercising judgment.
"Nevertheless I have somewhat against thee, because thou hast left thy first love. Remember therefore from whence thou art fallen, and repent, and do the first works; or else I will come unto thee quickly, and will remove thy candlestick out of his place, except thou repent. Rev 2:4-5 (KJV)
Please take your time and read through the other addresses to the churches and see how the character of the Lord applies to each one.