I think 38 is not a negative for Cristiano. We watched Zlatan again with his good performance at this age. Ronaldo can show this performance in the same way. It just takes a team that believes in it. He was 37 years old last year and had done well for Manchester United. Cristiano Ronaldo probably plans to play football until the age of 40. Later, he can step into his coaching career.
Ronaldo has already said that he believes that 40 years is a good age to retire. I think that this can be regarded as a direct confirmation that he will not end his career earlier.
As for his possible coaching career, I'm not sure about that. He is too ambitious and demanding of himself - if he makes at least 20% of such demands on ordinary players, then this will lead to nothing but conflicts.