The answers to this seemingly simple question are mixed. Tracking codes in Manager only apply to income and expense accounts. So you cannot maintain balance sheet records of fixed assets with tracking codes. However, you could assign fixed assets of various business units to different custom control accounts. See https://www.manager.io/guides/9256.
When you purchase new fixed assets, the purchase transactions can be assigned tracking codes. (See https://www.manager.io/guides/9106.) And, as @Abeiku has already told you, depreciation entries (see https://www.manager.io/guides/9119) can be given tracking codes, since these are expenses.
Currently, depreciation for all fixed assets is combined in the single Fixed assets, accumulated depreciation account. This makes it laborious to determine book value for assets reported in separate control accounts. So, in my opinion, there is actually little benefit to doing that. The Fixed Asset Summary is an easier method for determining that.