Should I use a Trek Domane SL5 for touring?
People tour on all kinds of bikes. That said, if you're going to tour on the Domane, you'll need to figure out how you'll be carrying your gear, since (as Argenti mentions in his comment), it doesn't have any mounting points for racks.
There are workarounds for mounting a rack (which come with compromises), and increasingly people are bikepacking—using frame bags, seat bags, and handlebar rolls that mount directly on the bike instead of traditional racks and panniers (which come with a different set of compromises). 10 kg of gear is probably close to the limit of what you could fit in a bikepacking setup.