Compressor belts slipping

Belt adjustments are DIY possible but some belts have autotensioners meaning no adjustment is possible nor required. If the belt is loose it has to be replaced.

https://www.2carpros.com/articles/how-to-change-a-serpentine-belt-video

If belt is adjustable, look for a pulley that is running along the A/C compressor and crank pulley belt. It would have a holding nut that needs to be loosened before you can turn the adjuster bolt at side for adjusting belt.