The RAW can get a bit weird for teleporting.
If we strictly follow the RAW for misty step, you would be naked after teleporting since it just says "You".
You teleport up to 30 feet to an unoccupied space that you can see.
Although hilarious, it would get old pretty fast. This is why most people interpret "You" as you and all your gear. If you had a treasure chest you would have to stuff everything you can carry in your pockets and leave the rest.
Then there are spells like teleport:
This spell instantly transports [...] a single object that you can see within range, to a destination you select. If you target an object, it must be able to fit entirely inside a 10-foot cube
This means that you can teleport with all your gear and you could bring the treasure chest as long as it fits the 10-foot cube, even if it exceeds your carrying capacity. Unfortunately, you can take only the chest and not the treasure since it states that it must be a single object.
But there are also spells like thunder step (XGtE, p. 168):
You can bring along objects as long as their weight doesn’t exceed what you can carry.
This would mean that you get to bring your gear with you and also the treasure chest with the treasure as long as you can carry it.
My point is: it differs from spell to spell. You should always read the spell description before teleporting and accidentally leaving your treasure behind. And of course, talk to your DM to make sure "you" means you and your gear, or your party might get stranded in the Elemental Plane of Fire, naked in front of a fire giant, if you cast plane shift.