Being annoying is the best way to draw aggro
Playing the role of a defender (aka tanking) is a clear fantasy identity in gaming, including TTRPGs. It's not typically cranking out big numbers, but it is appealing - your goal is to try and seize the momentum of the fight, and look like a badass doing it.
Within the TTRPG space, however, any player looking to defend their squishy friends will inevitably run into the Tank Fallacy. In brief, it is the idea that while a PC may be resilient, trading everything in exchange for defense makes the character unattractive to attack. If you are nigh unkillable but deal tiny damage, there's not much incentive for an intelligent enemy to target you.
Depending on the system, there are many options to help draw an enemy's ire. In D&D 5E, certain barbarians can cause enemies to be less likely to land hits on other targets. In Pathfinder 2E, the Champion gets a reaction to receive some of the damage targeted toward an ally. Both of these cases incentivize the enemy combatants to prioritize the defender as they will have a much harder time neutralizing the more damaging target.
There's many other options as well, most of which are based around denying movement of enemy NPCs or increasing damage.
Then there's my favorite: being a cheeky bastard.
Playing mind games
In my current campaign, I am playing a kitsune fighter who uses a kusarigama. He's not particularly tough, nor strong, nor does he have magic. He is 4'9" (1.4m) at the tips of his ears, and classifies as a flyweight. This is okay, though, because in Pathfinder 2E, status effects are common, and my character specializes in being annoying.
Just recently, my party was fighting an enemy caster and her summoned monster. I was hanging out in melee, positioned right between them so I could threaten them both. My kitsune's main weapon attack makes an enemy frightened, which applies a penalty to all d20 rolls the target makes. He can just keep an enemy frightened any time he hits.
He's also a Marshal (kind of a mini-class in PF2 called an archetype), so he has an aura that boosts everyone's chances to hit, including his own.
The enemy caster was leveling a spell against the group's sorcerer, who had just started blasting. This triggered a reaction from me to attack which was a critical thanks to these bonuses, which caused her to lose the spell.
And man, was she pissed.
Then my turn was right after her. I once again hit her with the frightened condition, and then tripped her to the ground. That frightening attack happened to be a critical hit as well, meaning the frightened condition was even more potent.
Her next turn, she had to take time to stand, and took out a sword to engage. Her attacks missed, at least one of them because of the frightened condition I had applied.
My kitsune has a feat which allows him to further debuff an enemy with a quip, which I threw at her as soon as it came back up to my turn:
"Am I annoying you?" With a cheeky grin.
She spent the next rounds and several spells trying to 86 my kitsune, and she eventually did... just after her monster had been neutralized. My party made short work of her.
To add insult to injury, my kitsune succeeded on self-stabilizing.
A very fun, unorthodox way to protect the party.