Man, I wish there was a single magic PDF floating around for that! It's not really a thing you just 'download' like a template, because a 'love contract' in those books is always super specific to the characters—like, is it a billionaire forcing a marriage of convenience to secure an inheritance, or a scorned heroine making her cheating ex sign a list of reparations? The legal-ish feel usually comes from the author weaving in those detailed clauses that mirror the emotional stakes.
What you might find are general 'prenuptial agreement' templates on legal document sites, but they'd be dead boring. The fun is in the customization. I've seen fans on Tumblr or Pinterest make aesthetic 'prop' contracts for their favorite books, like for 'The Love Hypothesis' or a dark mafia romance, which is probably the closest you'll get. Honestly, just describing the terms in your own words hits the same spot for me.