I'm not that into first person myself, and I have a large list of current and upcoming games I keep track on. To me, action is any sort of real time combat system, and third person to me is anything that isn't first person.
I was unsure if the OP meant a over-the-shoulder, isometric, fixed-view or what.
Regardless of angle, to me, what is important about third person perspective is that I can see my character and that matters to me, as a lot of my satisfaction from the genres I enjoy are often derived from smooth animations, character building, character customization and expression, where as first person shooters are often a lazy floating camera that doesn't feel rooted in the world.
I think the OP is missing out by dismissing current and upcoming games that also will appear on console.
The fact of the matter is that due to ease of porting, most PC third person games are by default ported to at least one console. It's easier than ever to do, which makes the idea of "PC exclusives" an entirely flawed concept.
There are games where playing them on PC might as well be a different experience all together. Jedi Outcast is a perfect example of a game that just doesn't play mechanically the same on console as it does on PC. It's absolutely insane to say the game is to be dismissed because it appears on console. I think that's genuinely crazy.
Practically speaking, it is very difficult to keep track on what gets released on which platforms.
Many of the KS and crowdfunding and early access titles have other platforms "TBA". Some titles don't end up getting released, others do. But increasingly I don't think it matters. Exclusivity is not really a beef PC has to have.
As for online, I'd challenge the OP by saying that the vast amount of online experiences today are tailored towards solo play, does not require a headset or are infringed by players.
In fact, it's a major recent development that has taken hold over the last 10 years that online games are being single player experiences themselves.
For one, by turning games into services, developers and publishers increase their ability to continually sell post-launch products after the game has shipped.
This makes sense from a financial and logistical point of view.
Secondly, by adhering to a online-enabled method of playing, players who want to pirate or crack the game illegally for offline play will have a hampered experience.
Some of these are online, some of these are for other platforms, some of these have buff military dudes like Max Payne, but I still think the OP should check these games out.
They all have action, they are non-first person. Some are not out yet, but those that are, are solid.
PC used to be known as the place that only had RTS and FPS and not much else, but the fact is that action combat has snuck into all manners of RPGs, survival, exploration and simulation genres.
And some of the best third person combat you can find at all, are in the third person games.
Already posted games like Black Desert are fucking awesome with their combat, despite being MMOs. Incredible high skill ceiling, insane animation transistions and impressive effects. Let it not fool or deceive you that because the game is online, that it's not on par with its offline contemporaries.
Death's Gambit [Hack'n Slash Sidescroller]
EITR [Viking Hack'n Slash]
Paradise Lost [Stealth Action Adventure]
Elder Scrolls Online [Action MMORPG]
Battle Chef Brigade [Side Scrolling Action Cooking RPG]
Lineage Eternal [Korean Isometric MMORPG]
Combat Core [Action Beat Em Up]
ARMA 3 [Military Simulator]
Absolver [Martial Arts RPG]
Mount and Blade 2 [Action RPG Medieval Simulator]
Lost Ark [Korean Isometric MMORPG]
Dark and Light [Survival Sandbox Online Action RPG]
Star Citizen [First and Third Person Space game]
Dauntless [Monster Hunter MMO]
Albion Online [Runescape-esque MMO]
Blade and Soul [Action MMORPG]
PLAYERUNKNOWNS BATTLEGROUNDS [First and Third Person Shooter]
Worlds Adrift [Sky Pirate Sandbox Exploration MMORPG]
TERA [Korean MMORPG]
Crowfall [Sandbox Action MMORPG]
Wildstar [Themepark Action MMORPG]
Smite [Action MOBA]
Moonlight Online [Chinese Action MMORPG]
Battlecry [Beat Em up]
The Black Death [Survival Action Medieval MMO]
Gang Beasts [Physics Beat em up]
Pyre [Isometric Action RPG]
Ruiner [Isometric Action game]
Tokyo 42 [Isometric Action Game]
Guild Wars 2 [Action MMORPG]
Below [Action RPG]
Knights and Bikes [Action Adventure]
Prey for the Gods [Action Adventure]
Jotun [Isometric RPG]
Dustforce [Sidescrolling Action Adventure]
Doko Roko [Sidescrolling Action Adventure]
Chasm [Metroidvania Sidescroller]
Warframe [Online Action RPG]
Deformers [Beat Em Up]
Mordhau [Medieval Combat Simulator]
Old Time Hockey [sports beat em up]
Planet Alpha 31 [Sidescroller Shooter]
Rain World [Survival Action Adventure]
Rise & Shine [Sidescrolling Shooter]
Scarf Walking with Souls [Action Adventure]
Serial Cleaner [Murder clean up simulator]
But this is just a tiny list. If you take in many of the early access stuff, the MOBAs, open world action titles, the usual AAA action adventures, and so on the list could go on forever.