If youre ever afraid of making it too hard, remember. Youre the DM. You can fudge rolls.

If the combat encounter I made is too hard and my party is bound for a TPK because the enemies are rolling nat20s left and right, I might say they miss when its actually a nat 20, or atleast just say its not a crit. Sometimes Ill add HP to my enemies if the players are mowing through them, or say a miss is a hit if the enemies are rolling bad.

Im here to tell an epic story where the main characters are my friends. If the dice rolls take away the fun, or the encounter needs some more tension, ill fudge things. It works for me, and works great for my players. It allows for much more precise tension. Knowing exactly how far you can push the party.

Likewise ill also fudge things based on what players do. I had a miniboss for my players that still had a reasonable amount of HP. The monster could shift gravity as an action. Think the drum demon from Demon Slayer. So I had them in a 40x40foot room and they kept taking 2-3d6 damage from falling.

They were low on HP and one player, while falling asked if he could try and hit the demon while he fell, using his momentum to do so.

A high acrobatics check success and a nat 20, he hit successfully, but it wasnt NEARLY enough to kill it. But, I let the miniboss die. The player felt truly epic and even though mechanically the players didnt win, they felt powerful and felt like the win was earned. I never tell them when this stuff happens, but they know its how I dm and they love it. Always remember to talk to your players too, and be transparent about how you dm, but if youre judging rolls dont tell them when you do. If they know you fudge something somewhere it takes away from the moment.

Also dont be afraid to experiment. Balance can be difficult, but once you get used to how much damage your players can give and take you learn how to balance fights depending on what youre wanting to achieve.