Here are some clues from the Old Testament that the church does not go through the Great Tribulation, i.e. the rapture is pre-tribulation.
Isaiah 26:
19) Thy dead men shall live, together with my dead body shall they arise. Awake and sing, ye that dwell in dust: for thy dew is as the dew of herbs, and the earth shall cast out the dead.
[Refers to the resurrection]
20) Come, my people, enter thou into thy chambers, and shut thy doors about thee: hide thyself as it were for a little moment, until the indignation be overpast.
[The resurrected Christians have a home in our Father's house - John 14:2-3. This verse alludes to the church being raptured and hiding during the tribulation.]
21) For, behold, the LORD cometh out of his place to punish the inhabitants of the earth for their iniquity: the earth also shall disclose her blood, and shall no more cover her slain.
[The Great Tribulation.]
Psalm 27:
5) For in the time of trouble he shall hide me in his pavilion: in the secret of his tabernacle shall he hide me; he shall set me up upon a rock.
[During the "time of trouble" the church will be hidden in God's house, and they will be set upon a rock, i.e. Jesus.]
Psalm 57:
1) Be merciful unto me, O God, be merciful unto me: for my soul trusteth in thee: yea, in the shadow of thy wings will I make my refuge, until these calamities be overpast.
[Again, alludes to the church being hidden during a time of trouble.]
Psalm 83 (MKJV):
3) They take shrewd counsel against Your people, and plot against Your hidden ones.
[The nations conspire against God's people Israel and plot against the church, who God hides by rapturing them.]
Zephaniah 2 (WEB):
3) Seek Yahweh, all you humble of the land, who have kept his ordinances. Seek righteousness. Seek humility. It may be that you will be hidden in the day of Yahweh’s anger.
[The church will be hidden during the day of God's wrath - the Great Tribulation.]
Another example, or type, is Enoch, who was caught up (raptured) before the tribulation of the flood - prophetic of the church being raptured before the Great Tribulation - the outpouring of the wrath of God.