There is NEVER. a cutoff for showing your son affection. My son is 11 and I live for the moments that he comes and lays in the bed with me and we talk about whatever the fuck for however long.
My homie came to visit a while back and said 'Son, I've NEVER seen a father and son say 'I love you' to one another as much as you and your son.'. Literally prolly 25-30 times a day. No exaggeration.
We'll both randomly tell each other throughout the day, since he's doing distance learning and I work from home.
One thing I refuse to allow is for my boy to grow up, look back on how childhood, and have to wonder if his father loved him. Or say that his father never showed that he loved him. Etc.
I had a daughter last December and it's the same for her. None of us are perfect parents. But for whatever mistakes we make, at the very least, our children should be able to say 'But through it all, I know for a fact that my parents loved me and did their absolute best, and taught me how to express love.'.