No; "anything" means "any object".
In the absence of special game definitions for terms, D&D 5e reverts to natural language in interpreting the rules.
The word "anything" is defined on Dictionary.com as:
- any thing whatever; something, no matter what:
Do you have anything for a toothache?
- a thing of any kind.
The word "thing" has many definitions/uses, but its primary definition is:
- a material object without life or consciousness; an inanimate object.
(Other dictionaries display similar definitions.)
In this context, what this means is that a spell like greater invisibility (when cast to target a single creature) turns the creature and any objects being worn (e.g. clothing) or carried (e.g. weapons) are invisible as long as the spell remains active. The word "anything" does not somehow make a single-target spell into a multiple-target spell just by the targeted creature carrying another creature.
Objects are defined in the basic rules/DMG:
For the purpose of these rules, an object is a discrete, inanimate item like a window, door, sword, book, table, chair, or stone, not a building or a vehicle that is composed of many other objects.
This generally matches the definition of "thing" above.
A question in the 2019 Sage Advice Compendium addresses a very related topic:
Some spells (like eldritch blast) target a creature. Some others (like fire bolt) target objects too. Does this mean that I can’t attack the door with eldritch blast?
The target specifications (creature, object, or something else) in spells are intentional.
In this case, greater invisibility clearly targets a single creature at its lower level, and allows the invisibility to extend to "anything" worn or carried by the creature. In this context, it clearly uses a term used to refer to objects, and doesn't mention the word "creature". If the spell's benefits were meant to extend to creatures carried by the target, it would clearly say so.