Mordechai Kedar and Edy Cohen (Main israeli political activists in Arabic media) Says that The Third temple Will come down from heaven, is not a human build, is there any evidence for that?
There isn't a standard belief about how the third temple is to come to be. There are various scenarios and viewpoints about the events and what we can or cannot expect.
The two main viewpoints you're referring to are split between the Rambam (who believed that the third temple would be built by man) and Rashi (who endorsed the idea the third temple would be created by Hashem and would descend from heaven)
It can be argued that part of the reason for the shift in opinion towards a heavenly temple is the political situation in the modern State of Israel.
The Third Temple cannot currently be built. The central issue is the political conflict around the temple mount itself. The temple mount is stuck in a religious tug of war between the Arabs/Muslims and the Jewish people/Israelis. Any change to the status quo of the current location creates a huge conflict with both local Israeli-Arabs, Palestinians, and the surrounding Arab states in the region. Back in 2017, there was an attempt to put metal detectors at the gates of the mount after a terrorist attack and there were riots for weeks.
Israel actually bans Jewish religious use of the location (up top) as a means to appeasing the status quo. You will be arrested for uttering a Jewish prayer up top outside of extremely specific circumstances. Israelis have been fighting this in court for years now.
Due to the current restrictions Israelis face in modern society regarding the mount, this has likely resulted in a shift toward the Rashi position since there doesn't seem to be a functional way of building the temple without a major conflict.
If we can't do it then obviously, Hashem will do it.
The main obstacle with building the temple currently is the golden dome sitting at the top.
The golden dome (built in the footprint of the second temple) blocks the location from Jewish use and we couldn't put the temple anywhere else since the focal point of the temple is where the original sacrificial altar originally was. The temple would be built where the dome is as the altar would sit in a specific location directly in front. This isn't an option currently.
This hasn't stopped organizations from forming which hold the Rambam's opinion. The Temple Institute of Israel is an organization dedicated to the building of the third temple. They have been funding the groundwork for years about how the temple will be built and preparing the necessary materials for temple processes.
If they were given the green light they would likely start building tomorrow. Their belief is it is a religious duty for the Jewish people to rebuild the temple and to restart temple processes. It doesn't matter if mashiach has yet to arrive as the religious duty is imperative regardless of mashiach's arrival.
The secondary issue with the rebuilding of the temple is we have no high priest and we have no Sanhedrin.
The high priest manages the activities of the Beit Hamikdash. We have no one who would be manage temple processes as a high priest doesn't currently exist.
We also don't have a Sanhedrin and the high priest was the head of the Sanhedrin. Attempts to have revived this body have failed so we don't have two major necessities for the creation of the third temple.
This is part of the reason why the "descend from heaven" opinion gains support. The Mashiach may be the only one who can truly establish the authority of the Sanhedrin once again and he will likely be the one who determines the priesthood and establishes and dedicates the third temple. There are too many unknowns which we would need to work through.