Ooh here are some! - walk in the park or take a hike - you can make it a picnic even if you just have PB&Js. Add a goal like birdwatching or plant IDing if you want to make it feel like more of a special activity. - go to a free concert wherever you can find it - on the lawn in the town center, at your local college’s music department, etc. - search for free things to do in your local area - sometimes just the initiative of suggesting/planning an activity makes it feel like a date
Picnic, walk in the park, going swimming, for a hike, the beach or lake (if you live near one), painting together, movie nights, game nights, go to free local events, antique shops ( my ex played this game with his friends where they’d separate and find the weirdest thing they saw and met back up😂)