In short, foreplay is everything leading up to actual intercourse.
There are no orthodox moral theologians today who would make such a claim, and the Church certainly has no such teaching.
That is the teaching of Saint Alphonsus Liguori.
When you add a luxurious feel to this, it makes the experience decadent and indulgent, which brings you towards focusing on your senses and being in the moment.
And while it's commonly accepted that foreplay should happen before intercourse, the questions of whether it does happen, how long it typically lasts, and how to spice it up and how to master foreplay are another story.
Take advantage of how sensitive the lips are with light kissing, tracing your finger, and gentle lip biting.