Copywriting is writing that promotes a product, a company, a person...And applied to LinkedIn, it's what will allow you to promote your post, make people want to read your publication or even go further by clicking on the link you shared. So you're going to write to be read.
Start with a catchphrase to attract attention, it can be a request for an opinion, a fact or just the announcement of the subject. The catchphrase is written on 2 to 3 lines.
Then for the body of the post, you can follow marketing models AIDA or NOT to write good copywriting and generate interest in your publication.
And always end with a call to action. that will elicit commitment (likes or dislikes).