The current definition of Thanksgiving is to express gratitude to those who have helped you. As for leaders, it is a bit exaggerated to give gifts on Thanksgiving. However, since they have helped you, as a junior, you can of course give a small gift to express your gratitude for the care of the elders. I can give you some advice:
1. If it is convenient, you can invite the leader to dinner and go to a better restaurant. You can relax yourself at the table and express your gratitude, and let the leader feel that you can handle things.
2. Simply give a small gift, you can buy a watch or something like that and give it to the leader. Although the leader may not lack these, your behavior will make him care.
3. For a more ordinary gift, you can give good wine or cigarettes that the leader likes. Giving these is not exaggerated, the leader also likes them, and the cost is not large.