The events in Acts are unique to the 1st century. It was a unique time, a time of transition from Judaism to Christianity.
From John McArthur's Commentary:
Many who teach that Christians receive the Spirit subsequent to salvation appeal to this and similar passages for support. Here is a clear example, they argue, of people who were saved, yet did not have the Holy Spirit. Such teaching ignores the transitional nature of Acts. (For further discussion of the transitional nature of Acts and the issue of subsequence regarding the coming of the Spirit, see my book Charismatic Chaos [Grand Rapids: Zondervan, 1992].) It also flies in the face of the plain teaching of Scripture that “if anyone does not have the Spirit of Christ, he does not belong to Him” (Rom. 8:9). There is no such thing as a Christian who does not yet have the Holy Spirit, since “by one Spirit we were all baptized into one body” at conversion (1 Cor. 12:13).
Why did the Samaritans (and later the Gentiles) have to wait for the apostles before receiving the Spirit? For centuries, the Samaritans and the Jews had been bitter rivals. If the Samaritans had received the Spirit independent of the Jerusalem church, that rift would have been perpetuated. There could well have been two separate churches, a Jewish church and a Samaritan church. But God had designed one church, in which “there is neither Jew nor Greek, there is neither slave nor free man, there is neither male nor female,” but “all [are] one in Christ Jesus” (Gal. 3:28).
By delaying the Spirit’s coming until Peter and John arrived, God preserved the unity of the church. The apostles needed to see for themselves, and give firsthand testimony to the Jerusalem church, that the Spirit came upon the Samaritans. The Samaritans also needed to learn that they were subject to apostolic authority. The Jewish believers and the Samaritans were thus linked together into one body.
Today, believers receive the Spirit at salvation (cf. 1 Cor. 12:13). There was no need for delay after Jews, Gentiles, Samaritans, and Old Testament saints were already included in the church.
MacArthur, J. F., Jr. (1994). Acts (Vol. 1, pp. 244–245). Moody Press.