I am not sure if I can explain beyond wanting this feature (I plan to introduce a new product in about a months time with a post and would like the subject line hyperlinked to the product.).
phpBB has never allowed HTML in board content due to security issues. You can make a forum description a link, or you can put a link in a topic body or signature with BBCode.
I can stop all your spam. I can upgrade or update your Board. PM or email me. (Paid support)
Have you noticed that every subject already is a link? What you want would nest them.
"The problem is probably not my English but you do not want to understand correctly. ... We will not come anybody anyway, nevertheless, it's best to shit this." Affin, 2018-11-20 ↑
"But this shit is not here for you. You can follow with your. Maybe the question, instead, was for you, who know, so you shoved us how you are." axe70, 2020-10-10 ↑
"My reaction is not to everyone, especially to you." Raptiye, 2021-02-28 ↑