End Game

@BatGroot13 Also, level 27 is the highest level. It doesn't matter whether you've finished the game or not, if you do things which earn experience, you can continue to level until you reach level 27.

After completing the main quest and the celebration afterwards, your companions can be found in their usual places, but they will only have something to say once, after that they will only greet you, no other interactions (such as romance options) will be available.

If you have DLC quests to do or non companion quests (such as completing collections, killing dragons, etc), these can be done after completing the final mission.

If you have Trespasser, starting the Trespasser mission will take you away from Skyhold and 2 years into the future, you will not be able to return after doing that. Trespasser can only be started after completing the main quest.

After you finish the final mission, you can use the Golden Nug to upload your collections and schematics, making them available to future characters if you choose to.