I figured out by copying this level. Looked complex but I found it's very simple.
I was searching for a guide but I could find nothing. So I decided to publish a guide by myself.
Timestamps
0:28 Push the box to the left and tread it. 1st coin.
0:53 2nd coin.
2:10-2:14 Turn back. You can get the 3rd coin.
Hiroquet currently has 166,987 views spread across 2,132 videos for Geometry Dash. This game accounts for over 3 days of watchable video on his channel, or 82.99% of the total watchable video for Geometry Dash on Hiroquet's YouTube channel.