Ronaldo is already old and might have a good reason why he doesn't want to partake in the club world football and I don't see anything wrong about his decision. Of course, experience in needed in football much more than strength because lack of experience can make a player miss his opportunity of scoring a technical goal.
Things are really strange to see that CR7 doesn't want to play, he already won the Nation League, he left many people speechless at how a 40 year old man beats a 17 year old boy, you can see his power there, besides it would have been crazy if CR7 had played because he would have sold a lot, and that was what Infantino wanted, but since FIFA has always been so inconsiderate with the best in history, CR7 pays them like that.
Had it been established from him about his willingness or unwillingness to participate, because am seing the two of them, both Ronaldo and Messi to participate in the world cup and this may be their last one to participate in, consider lots of factors, age and the rest, but like seriously am more interested to hear from a reliable reference what Ronaldo is talking about his participation in this world cup.