You can replicate adjustment layers by using blending modes. As you know, Gimp has lots of blending modes, I mean more than Photoshop.
Before we begin with the article, let me be clear on one thing: this method does not create a full copy of Photoshop's adjustment layer, but only several important ones.
In this article, I duplicated the effects of about half of the adjustment layers in Gimp, which will help you with image manipulation, image correction, and other work.
Darken (Levels, Curves, Exposure)
To darken an image you might use levels, curves, or exposure adjustment layers, but to recreate this exact darkening effect you can use plenty of darkening blending to do that, but my recommendation is to multiply.
To replicate this adjustment layer.
Step 1. Create a new layer
Step 2. Fill it with black
Step 3. Change blending mode to multiply
Step 4. Reduce the opacity to adjust the darkening effect.
Brighten (Exposure , Curves and Levels)
Step 1. Create a new layer
Step 2. Fill it with white
Step 3. Change blending mode to overlay
Step 4. Reduce the Opacity to Adjust the Effect
Contrast (Levels, curves, and brightness and contrast)
Step 1. Duplicate the layer
Step 2. Change the blending mode to Overlay
Step 3. Reduce the opacity to adjust the effect.
Color Match (Color Balance, Curves)
Step 1. Create a New Layer
Step 2. Use a color picker tool with a high average sample rate (pick the area where the image is not too bright and not too dark).
Step 3. Fill the sampled color on the new layer
Step 4. Change the blending mode to Lch Color
Step 5. Reduce the opacity to adjust the effect
Invert
Step 1. Create a new layer
Step 2. Fill it with white
Step 3. Change Blending mode to Difference
Black and White
Step 1. Create a new layerStep 2. Fill it with black
Step 4. Change blending mode to LCH Color (If you reduce the opacity, then you can also use this method to desaturate your images).