Help me to understand English! 28.1☘️

2. They wanted to stop being pirates.

This one is not grammatically correct

3. But I don't want to play in the sun today any more.

The speaker is currently playing in the sun, but would like to stop

4. But I don't want to play in the sun today again.

This speaker played in the sun earlier, went inside and does not want to go out and play again.

5. Then they came into their nice house, whereich had a small garden with beautiful flowers.

Grammatically incorrect. Movement from outside to inside requires the word "into". The house is still the subject in the second phrase, so we use " which" instead of "where"
"Then they came into their nice house, where there was a small garden with beautiful flowers".

7. Then, a big lorry stopped outside the home opposite

The lorry is big, not small. It can be quiet or loud.

8. Then, a loud lorry stopped outside the home opposite.

The lorry is loud, it makes a lot of noise, but can be big or small.

9. Some people go fishing as a sport to know who can get/catch the biggest fish.

This doesn't sound very natural, although it is grammatically correct. Instead of "know", I would use "find out" or sentence 12.

Some people go fishing as a sport to see who can get/catch the biggest fish.