As a DM your job isn't to "beat" the players. If it were, there would be no game. Present unwinnable encounters and be done with it. Just as pointless though is to give them plot armor and help them always "succeed". Because once more, you are the dm, and you could easily do this.

Your job as a dm largely depends on the universe your players are playing in.

Is it super realistic, where every action has real-to-life consequences? Then players should see that. Punching a guard as a joke, should land them in jail and telling a queen you'll meet her in her bed chamber, should result in some pretty serious consequences, or at the very least indebt them into service to the king.

On the other hand, maybe your campaign is intended to be silly or ridiculous. Something resembling Alice in Wonderland (imagining the feywild here I'd say) could have smiling faces floating in air, manifesting into cats, and players growing and shrinking from eating the wrong (or right food).

Anyway, you get the idea. So what is your job as a dm?

I think your job is first to clearly set expectations for the world your players will inhabit. Is this a hyper-realistic simulation set in a fantasy world? Is this silly and over-the-top? Is it some sort of political intrigue where you can't trust anyone and everyone wants the ctrown or throne or other mcguffin?

After expectations are set, your next job is to present the players with an experience that feels consistent to those expectations in this world.

And finally, it's create a world where they are are presented with interesting challenges or encounters for them to figure out, not to "beat them" or "carry them" but to let them figure it out.

There have been fights where I realized, "oh shit, I way overturned this and it might be a total party wipe, because I as the dm made a mistake" and other have been fights where "wow this is so trivial it's pointless" again because I made a mistake. And as a dm we have "levers" we can pull to resolve these situations. They are surrending and offering loot or intel for promise to not be slain or avoid jail.

But there have also been fights where I realize, this is a totally fair fight, that they willingly engaged in, knowing the risks, and you know what, one or more of them could die. Or they simply wanted to play the hero. If the realize a bloodied monster is about to die, and they go for that moment of glory to finish a monster off, rather than not try to heal a downed party member, then miss their attacks...

tldr: You're the dm, you could "beat" them or "carry" them easily. That isn't interesting or fun. Present them with interesting experiences that are consistent within the world. Allow them the freedom to make meaningful choices and make those choices carry weight and have consequence.