Wechat provides a video slimming function, which can compress the video before sending to reduce the file size. Here are the steps to turn on video slimming in WeChat:

Open WeChat: Open the WeChat application on the mobile phone.

Enter the chat interface: select the chat dialog box to send the video.

Click the "+"button: Click the "+"button below the input box of the chat interface to open more sending options.

Select "Album": In the sending options, select "Album" option to enter the album page.

Select Video: On the album page, select the video to send.

Turn on video slimming: After selecting a video, you will see a "slimming" button in the lower right corner of the video. Click this button to open the video weight loss function.

Wait for the compression to be completed: WeChat will start to compress the video, and you need to wait for a while until the compression is completed.

Send video: After video compression, you can click the Send button to send the video to the other party.

Please note that the video slimming function will reduce the quality and resolution of the video to reduce the file size. Therefore, before turning on video slimming, please make sure that you can accept the reduction of video quality. Due to the different video size and mobile phone performance, the compression time and compression effect may be different.