If you need to increase the size of a picture and you don't want it to appear pixelized, you may want to use a specific program to resize photos.
These programs try to calculate how an image would look like if it were bigger, by adding an extra pixel between two of them. Reshade mainly fades the picture in order for you not to see the single pixels after zooming. It doesn't really maintain the graphic quality, it just creates a smooth effect which lowers the image definition. Although this can be acceptable for reduced zoom needs, it will not look good with greater zoom.
There are some options you can modify like quality, that doesn't change much though, smoothness, texture, accuracy and threshold which instead make an immediate visual difference.
Reshade allows you to increase the size of you photos without having to suffer much from the pixel side effect of the zoom. Although it doesn't maintain quality it will be good enough for minimal enlargements.