Yes, the added weight is taken in account for the majority of the measured metrics automatically without the need to enter it anywhere (though you can use the Notes for doing so), since it increases your HR and respiratory rate, and decreases the HRV. Only the VO₂max and some derived metrics won't be adjusted - Garmin currently does not have any methodology for including the added weight into the VO₂max calculation, and I am not sure whether there are some mathematical models already available for that, in the scientific literature. For that reason, you may want to use a copy of the Trail Run activity profile with the VO₂max option disabled, when carrying the weight.
