I recently attended a seminar by a Partner, who dealt with a topic that came quite handy to me recently, quite beautifully. I would love to show my appreciation to him for the same (since it was online, I could not attend it in person, but would still like to tell them thank you).

Is it okay to email them (from a personal ID ofc) or just drop in a LinkedIn message showing my gratitude?

Hi!

I do not think it should be an issue. Go for it.

LinkedIn message should do, these partners judge every email they receive from a law student nowadays. Be crisp and formal about it and don't try to beg for an internship because they see through it all my friend. Best of luck!

You know an industry is screwed from the top when poor students need to even ask for such questions, lol.