Essentially, yes, in spite of the deformation due to Obelix being fat well wrapped compared to others Gauls' pants in the comic.

These pants were called bracatae by Romans (from Gaulish *braccas or *bragicas), and while they weren't really particular to Gauls (Medes, Persians, even Hebrews had similar trousers), they considered them specific enough of transalpine people that they nicknamed their province in southern Gaul "Gallia Bracata", the "Gaul in pants", something that both Greek and Romans found unfashionable, barbaric (being a trope of representations of Gauls and Germans) and silly-looking, which didn't prevent their adoption by servile and military forces of the Empire in Late Antiquity (altough still frowned upon by Italian upper classes as far as the Carolingian era)

Obelix's colourful clothing also echoes an historical reality : while official tunics (as in the rest of the Mediterranean world) were rather purposefully simple and/or white (at least for the Druids, quite possibly for magistrates and delegates in assemblies), Gauls famously loved coloured clothing and varied patterns, as evidenced by the Hallstatt steath, but as well by ancient authors such as Diodorus Siculus^(1). Probably not all were coloured or with sophisticated patterns, however, and could look more like this.

They bore these outfits as well in everyday life as battle, with mail armour^(2), an equivalent to roman sagum, a leather apron, but sometimes sometimes, as Obelix, without protection and with a naked chest (which is probably what must be understood by "naked warrior" in Livy, rather than litterally naked).

That said, braccatae could, as in Astérix, float and cover the whole length of legs but as well being tight to the knee and float from there, or being tightened to the ankle. That's about the big difference one could spot in what remains a comic device rather than a strict historical restitution.

^(1) Book V, 30

Their garments are very strange; for they wear party coloured coats, interwoven here and there with divers sorts of flowers; and hose which they call Bracae. They make likewise cassocks of basket-work joined together with laces on the inside, and checquered with many pieces of work like flowers; those they wear in winter are thicker, those in summer more slender.

^(2) Reconstitution made by Thibaut Gagnage