Writing Practice (Could anyone please check my sentences?)

"I had the car dealer check my car." and "I got a regular vehicle inspection." are the same, so having them in one sentence is confusing, like you're saying the same thing twice.

2) My hands smell a little bad because I cleaned some fish for dinner today.

Perfect!

3) Her intimidating words somewhat scared me. In the end, our friendship ended immediately quickly.

Immediately is VERY fast, and sounds strange, unless you have an event or reason directly linked to it.

She killed my dog, and our friendship ended immediately. Good

Our friendship ended immediately after summer break. Good

Our friendship ended immediately after she intimidated me. Good

"Our friendship ended immediately" with no event sounds like you met her for the first time, really liked her, and then hated he 1 second later. Strange. You say "In the end" too, which makes it sound like "after some time", which isn't immediately.

4) He used to do judo in his school days, and he [holds/has] a black belt in it.

Perfect. We would usually say "has" instead of "holds", but both are okay. "Holds" sounds formal, "has" is casual.

5) A friend of mine told me that said "It's a little bit hard for me to recognize who you are after you take off makeup."

"that" is used for indirect quotes. If you want to make an indirect quote, the sentence would be.

A friend of mine told me that it's a little bit hard for him to recognize who I am after I take off the makeup.