When you take Mathew 24:29-31; Mark 13:24-27, 1 Corinthians 15:51-58 and 1 Thessalonians 4:13-18 these verses leave no doubt that Christ does return on the last day.It's exactly like you said, Matthew 24:29-31 is about Jesus' return on the last day of this world, which is immediately after the tribulation He pointed to in verse 21. Those who have the hardest time with that simple Scripture are those who are taught to disregard it, those on a false Pre-trib Rapture theory from men.
But just in case you might not know, what Jesus taught there in Matthew 24:29-31 and Mark 13:24-27 directly parallels what Apostle Paul taught in 1 Thessalonians 4 about the event of Christ's coming and gathering of His Church. That is revealed by looking closely at the very last phrase of from where each group is gathered (per Matthew 24:31 and Mark 13:27). So Apostle Paul was pulling directly from Christ's teaching about the so-called rapture event.
All these so called famous pretrib teachers try to us Rev 4:1 to prove that of a pretrib rapture of the Church, but neglect vs. 2 that John was only caught up in the Spirit when these visions were given to him and not literally taken up to heaven, John 3:13.
Rev 4:1 After this I looked, and, behold, a door was opened in heaven: and the first voice which I heard was as it were of a trumpet talking with me; which said, Come up hither, and I will shew thee things which must be hereafter.
Rev 4:2 And immediately I was in the spirit: and, behold, a throne was set in heaven, and one sat on the throne.