Trying to figure out chicken tikka masala seasoning

Thank you for the info. This is the garam masala I have if it helps with additional comments and advice. https://www.frontiercoop.com/spices-and-seasonings/frontier-garam-masala0-5-oz

Just want to add a brief word to the wise about turmeric; it can skew very bitter so I would be carful about adding it in the same proportion as many other spices. I agree with some of the other comments that it’s a good idea for your first time to find a good recipe and follow it, but for future reference, when I improvise I tend to start with just a little turmeric and add a bit at a time. I’ve gone overboard with it in the past and ruined dishes. Anyway, best of luck!

Every household, restaurants have a different recipe for the garam masala. But doesn’t matter the recipe the ingredients remain the same it’s the proportions that change. This is a basic small batch garam masala recipe that I often use.
Ingredients -
2 gm Cinnamon
2 gm Cloves
7 gm Green Cardamom
1 piece Black Cardamom
1/4 tsp Nutmeg
1 pinch Mace
1 gm Dried Bay leaves
1 gm Dried Red Chillies
2 gm Black Peppercorns
* Heat a heavy bottom pan on medium flame, add all the measured spices.
* Dry roast them, stirring continuously for about 5 mins or till nice & fragrant.
* Blend it all using a spice grinder or mortar & pestle.
* Store in a air container.

There’s no coriander or cumin in this recipe so it’s more intense in its flavor. You can start the recipe by adding 1/2 tspn of this masala, along with coriander & cumin powder (I would highly recommend grinding the coriander & cumin at home then the readymade powders.)
Turmeric if added too much can taste bitter so start by adding 1 tspn.
You can add chili powder according to the level of spice you can handle. It’s always good to start by adding a little as garam masala has peppercorns which do add a little heat to the final dish.

Your reaction to the different recipes is natural - it reflects the reality that almost every household, cook and restaurant has its own version (see some history in Wikipedia article linked below).
Adding a tablespoon each of turmeric and chili powder at the start seems risky to me.
Rather, I would a recipe of chicken tikka masala you like or are used to (by chef, restaurant, whatever). Use that and start cooking. Taste as you go and then, or after left a day in the fridge for flavors to blend, add more spice if you see the need. Add gradually - a teaspoon at a time, cook some more, taste.
Or, if you like turmeric, consider this recipe - not chicken tikka masala, but very good.
https://food52.com/recipes/82155-one-skillet-chicken-turmeric-rice-recipe
https://en.wikipedia.org/wiki/Chicken_tikka_masala