According to the devs yes.

Why isn't "Hell no" an option.

Honestly, the skill level of different assassin's will always be debated as their skills are only comparative to the tech level at their time. The use of guns offsets the skill level needed with swords, hidden blades, etc. The only type of combat that could be comparable is hidden blades (since nearly all characters use them) and hand to hand. And even then there's so much to consider when comparing any two characters who are in the series let alone different time period

It's not so much that their skills are only comparable to the technology level of their time so much as it's difficult to compare across two different media. It's why I always take issue with these character skill contexts in other franchises like Star Wars, where the scaling for superhuman capabilities of Force-users vary extremely wildly between media, ranging from being no better than regular swordsmen with some magic in the movies to fighting faster than the speed of sound in the novels like anime characters. Kassandra in the novel is strained from fighting only 4 soldiers at the same time but can be played as a one woman army in the game.

Even within a single video game series, you have to account for different power scaling between installments due to contrasting gameplay systems affecting the presentation of skills. Ezio can't sidestep bullets in Revelations and to dodge those shots from Janissaries, he has to release his parry to pace around until the Janissary misses. Arno can only evade shots by rolling constantly. Evie and Jacob can literally dodge automatic bullet fire without looking. Connor, in the other hand, can only use other enemies as human shields against the gunfire. But these differences should not be taken literally. They are different gameplay systems, with older games generally being more limiting.

People used to argue that Altaïr and Ezio would be instantly gunned down by firearms, so they must necessarily be inferior to Jacob, Evie, and all other modern Assassins. There's no reason why they would not be able to adapt quickly to rapid gunfire, and they both lived in eras where rudimentary firearms had already been invented. Also Ezio did do a mission where he had to survive against Leonardo's machine gun.

Taking into account gameplay limitations, I would honestly imagine that Altaïr, Ezio, Connor, and Arno all had similar physical capabilities to Jacob and Evie, if not better. Since Jacob and Evie prove that canonically, Assassins are able to literally dodge bullets, I would imagine Ezio and Arno's instinctual senses made it possible for them to learn to do so as well.

All this aside, it's hard for me to imagine that Arno was as skilled as Ezio just because Ezio is legendary, but that's partly a bias. "Informed ability" (that Arno was the best Assassin) shouldn't be discounted outright since they do have canonical weight. At the same time, they can be disproven objectively if there is a way to directly compare two characters' limits or to compare their limits to a standard reference, and the character the author informs us is superior underperforms.

Most likely, Arno was more skilled and talented than Ezio in some areas and not as skilled and talented in others. Arno could perform double assassinations using only one Hidden Blade. Ezio has proven to be able to defeat multiple enemies in open conflict even while completely surrounded.

^Poppycock! That's just sales talk.

"Check out our new product. It's our best yet, nothing in the market compares."

Jk 😉.. well somewhat.