I am an 11+ tutor.
He is 7. Please do not start him on loads of workboooks and worksheets now.
If he is good enough for grammar school then he needs to do tutoring with parents or a tutor in year 5 to get ready for the exam. But doing loads of NVR and VR worksheets from a young age is soul destroying. And it is not the best way to learn.
Before year 5, the best things you can do are NOT worksheets etc but some of these:
reading. reading to himself at least 30 minutes per day, read all sorts of books, fiction and non-fiction, poetry, all genres and books from all eras (classics plus modern books). Turn off all screens and have a half an hour family read time, you sit down with a book and so does he. Make sure he is reading at his level, not too easy and not too hard. He should be coming across new words in his books, but not more than one or two per page.
reading to him - read aloud - books that he cannot read for himself, good chapter books, build his passive vocabulary and his comprehension.
Talk about books. Ask about the story, get him to predict what is next and what he thinks will happen. Ask how he thinks someone in the story feels, what they might be thinking. Who is the main character? What is the theme of the book? Where is it set? If the book is old, how do I know? What clues are there? (candles, horses, lack of tech, old vocab)
Maths - mental maths of all sorts, go to the shop, calculate how much 2 or 3 things cost, calculate change, work out savings and how much more do I need. Use 12 sided dice (easy to get on Amazon) and use to learn times tables, don't just do 3x4=12, but also do 12 divided by 4 = 3. Don't do times tables only as counting (eg 3, 6, 9, 12) but learn the fact 2x6=12.
Learn to tell the time on an analogue clock, to calculate how many minutes until we leave for school, or until dinner. Take away minutes and add on minutes. Learn the 24 hour clock.
Do baking and learn grams and kgs, and ml and litres. Measure and weigh. Measure things round the house, how long is your desk? The hallway? The garden? Use cm and m and mm.
Be intentional about using correct maths vocabulary.
Vocabulary (many of these work well on car journeys) have a word of the day - give out a sweet for anyone who can use it correctly in a sentence during the day.
Play synonym games - I had a big cat. I had a large cat. I had a huge cat. I had an enormous cat. I had an immense cat.
Play antonym games - I had a huge cat and a minute mouse.
Play collective noun games - I have a pack of...... (dogs, cards). I have a bunch of..... (bananas, grapes, flowers)
Play adjective games. I went to market and I bought - orange shoes
I went to market and I bought soft, orange shoes.
unusual, soft, orange shoes
expensive, unusual, soft, orange shoes
play adverb games - choose an action - singing.
Can you do this action - (then someone chooses an adverb) eg loudly
can you do it softly/ repeatedly/ quickly/ expressively
The next person chooses an action, and you choose an adverb