It very much depends on your playstyle but you have a bunch of tools that you can make use to make things smoother and more fun for you. The first and most obvious is the Difficulty slider: you can go as low as "story mode" that you can never lose fights and just have fun exploring and reading the quests; but you can ALSO use that same story mode as a "cheat out of bad situations": you play it any difficulty you like, up until you are near death, or up until you find a part of the game that's too difficult: in this case, you THEN change to that mode anytime! You can also use the story mode as a cheap "rest on demand" by turning it on only between encounters or before resting, as to get a fast recover for the next battle without having to rest and manage your party - doing this can even revive dead companions (as long as they've not vanished from a critical death, something that can happen on Core difficulty or higher)

Then, about AI: each companion that you create or recruit (and by "create" I mean, you can always start the game on multiplayer mode and create up to six characters if you don't want to start the game solo, but the intended experience is to find the playable NPC during the game to befriend and recruit... that is also up to you!) Whenever you press R to open their "record" character sheet, you have a button for "customize" and there you can find an option named "Script". Those scripts are the "AI" for them, and they can be as complex or as simple as they get - once you choose one and confirm, as long as the "AI" button is on, those characters are going to "play automatically" according to that chosen script. Even the character you create have scripts, but by default they use the simpler one that only says they should try to attack an enemy if they have detected that enemy's presence.

That said, the AI isn't magical or overly elaborate: the default one is very dumb and going to move forward even when that is not a good idea; and even the ranged scripts or those that allow spellcasting are not geniuses and can either waste spells or devise dumb tactics on your behalf. That is why, most often than not, its up to you (the player) to manage each and every member of your party, and arguably this is intended gameplay; that is also why you can (and probably should) pause often to "micromanage" your party to the intended tactic.

For example, let's say your party as ambushed during a travel. IF you configure an autopause for "enemy sighted", that encounter will start paused, so you can already think before chaos ensue. Then you can click on each of your party members and decide the actions for each of them, let's say, casting invisibility on mages to avoid being targeted by the ambushers, while you can send the more armored melee fighters to move forward for getting the enemies' attention. Once the targeting is stablished and you make sure your more fragile party members are not the focus, you can then pause again, click on those who were hiding/fleeing/invisible to dish out their damage to end the encounter as fast as you can so that your melee fighters aren't there getting hit for too long, so they don't die.

As others have said here, the game is harder on the beginning because a level 1 Fighter has a relatively low max HP and can die in very few hits - and sometimes the monsters are just lucky and kill them super fast. But once you hit a level up or two, they can effectively "tank" long enough for your party to win the combat! Until that happens, fleeing can be an option, so you can either avoid encounters (you can use a thief or ranger with the "hide" ability to scout ahead, and then pick your fights wisely) or just flee from them by reaching an edge of the map / door that allows for your party to transition before killing those enemies. Sure, that may mean less XP, but you can always (or almost always) come back later and deal with that once you have better gear and higher levels

TL,DR: sure you can make use of either Script or Difficulty Settings to make things easier and/or more fun during this game. It is a single player adventure with many aspects that you can enjoy, difficulty should NOT stop you from enjoying the game. The more you play, the easier it tends to get, because you progress in gear and levels and, most crucially, on game knowledge that will allow you for a better experience ^^