Clothing can be an important part of any fight scene. Honestly, most fights aren’t an elegant display of skill, they’re a scrabble dash where the attacker and defender are latching onto anything that gives a good grip. Clothes are great for that, grabbing someone by the shirt collar can be an excellent lead in to snagging them by the throat. You don’t have as far to go and it’s easier to hold onto while they are trying to run away. The collar will rip, but it serves it’s purpose. You even get the lovely psychological snag for their brain as they’re caught between flight: “I need to run away" and value: “wait, I can’t ruin my shirt!“, by the time they’ve managed to sort it out they end up standing there with a rather puzzled expression on their face. This is if you’re just still standing there holding their shirt, not if you’ve already taken the initiative in the confusion to put them on the ground.
Don’t ever underestimate the power of psychological persuasion, fighting is just as much about messing with someone’s mind as it is about messing with their body.
And I wouldn’t worry about the pants too much. Get the right kind of the jeans (a little loose, a little large) that are well-worn and used and it’s not hard to be able to kick above the head or someone else in the head in jeans. (So, long as they’re barefoot or wearing sneakers or shoes with good support.) I know that from personal experience. The trick is having a character who is limber enough that they won’t hurt themselves doing it cold (harder) or without a warm-up and has good enough balance that they can do the full twist, spin, or hip turnover in their sneakers on asphalt, cement, gravel, or dirt (harder).
They may have to change their fighting style up depending on what they are wearing. Such as hiking up or tearing a skirt, kicking off their heels, being forced to drop or toss away their purse or shoulder bag (if they do anyone can take it) because of the way they imbalance the body. Worry less if it’s a backpack, which are designed to be more stable. They may even have to toss away a jacket or divest themselves of a tight top, depending on how restrictive they are.
Keep in mind that anything they throw away while their fighting is an object that anyone else wandering by the scene from the bad guys to a random bystander can take or could get them in trouble if the cops arrive and they’ve fled the scene. A kick to the head is essentially a kill strike, at best a solid connection will cause brain damage by knockout, at worst the character could be doing a kick like a wheel kick which is designed to sever the brain stem.
So, try to consider the level of force the characters require to win versus what would sound or seem most impressive to the reader. A kick to the head is an impressive display of skill, speed, accuracy, and power. It’s also incredibly hard to control in a way that will not do significant harm to the other person, this gets even harder to do with spin kicks. Most spin kicks in Taekwondo, for example, are designed to be head shots.
If your character is using more force than required, they will be more likely to be held accountable by the local law-enforcement if they’re caught and will have a harder time pleading self-defense. Even when the others attacked first. Measure and mete out the level of response to the skill of the attacker as a sign of your character’s control. You’re less likely to overdo things that way and off put the reader.