I have an Epiphone Les Paul Custom and it's tuned in standard C and my playing style is mostly Desert Rock. I'm using a set of 0.12 strings and considering changing to a 0.11 set to have less tension on the strings and for the strings to be easier to bend. However there seems to be a small loss of tuning when using 0.11 strings.
Are there any guitar settings or anything else I could be doing to prevent the minor loss of tuning?
You should take your guitar to a professional guitar luthier or repairman and pay them for a setup.
Because you have changed from one gauge of strings to another, in order for your guitar to play in tune and for the strings to be the same height from the frets and fingerboard (what we call the "action"), your guitar truss rod will have to be adjusted to slightly change the amount of bend or "relief" in the neck.
Also, assuming we are talking about an electric guitar, the position of each of the six bridge saddles will have to be adjusted to recalibrate the speaking length of each string, using the appropriate screwdriver or wrench in conjunction with an electronic tuner.
If the electric guitar has a tremolo system, the spring tension on the back of the mechanism may need to be similarly adjusted to enable the bridge to sit in the proper position.
In some cases the nut may have to be replaced or the six string slots in the nut may have to be deepened or widened with special files.
Do not worry; all this is normal. Guitars are designed to be adjustable so that a professional can calibrate the guitar to accommodate whatever gauge of strings you prefer to play. But every time you decide to go with a different gauge, a setup may be necessary.
