Should I use a Trek Domane SL5 for touring? I am planning for one week/ two weeks long bike touring, mostly on the road with a moderate amount of riding uphill (mainly in Japan).
My weight is around 60kg. All of my touring gear won't exceed 10 Kg of weight.
I am planning to buy a Trek Domane SL5 (because of its endurance characteristic).
I am prioritizing the following facts to consider for a bike for touring:

Comfort for a long ride.
Durability
Budget-friendly but still not outdated.
7~21 days touring

Is it okay to choose a Trek Domane SL5 2021 as a touring bike?
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.