EPL, Bundesliga and Champions League are easiest because they’re on regular TV outlets. Get him to tune in today and next week for the semis of the UCL. Most of the players on the field in those games will be representing their country in June/July in Russia.

I’d bet decent money he quickly becomes a fan of Mo the fro Salah.

Fantasy PL is the best.

I printed a large poster sized chart a week before the matches began in Brazil and hung it in my family room. My kids were 7 and 5 at the time. I let them alternate filling in the results. As the tournament progressed, they started getting into it more. They’d come home from school / Summer camp and ask what the result was of a particular match. I’d DVR what I thought would be the best match of that day and we’d watch it when we were all home. I’d catch them studying the chart from time to time. When the Women’s World Cup rolled around the next year, I printed another chart. After the US won, my daughter hung it in her room.

Here are some links:
Daily Mail
Mirror
Sportwetten24

When it gets closer to kickoff, there will be more options. Some really well designed charts will become available.