Jaw & Chin
Once again I went with a low and narrow look on Garrett's features, so if you want to replicate his jaw shape you will want to position the dot centered on the fourth line down from the top, and on the left side of the second column from the left.
Garrett's jaw is actually slightly shallow in the slider for the Red Dead Online character builder, it is set on the left side of the fourth square from the left.
Garrett's chin shape in Red Dead Online is very narrow and tilted slightly high. To replicate it for your character set the dot just a tad high on the third line down from the top, and on the right side of the first column of boxes.
Garrett's chin is extremely shallow, so the dot is slightly right of center in the last box of the Chin Depth slider in the Red Dead Online character builder.
Garrett's ears are Neutral, with the Ear Shape and Ear Size both perfectly centered in the grids.
Ear Shape & Ear Size
Since these are both set to center I combined the grids onto a single image for this one.
Eyes & Brows
Mouth & Lips
Upper Lip Shape
Lower Lip Shape