You're welcome, June is awesome, the lakefront will be busy with lots of water activities and walking or cycling along the lakefront is lovely. Lots of boats, jet skis etc along the lakefront.
There will be lots of shows and concerts etc around the city.
@CatsLikeBoxes is right about the summer fireworks every Wednesday and Saturday evening at Navy Pier, this year they had some drone shows so I'm not sure if they are planning to replace the fireworks with drones but both were great.
Navy Pier also has the Chicago flyover which I tried a few months ago and thought was really cool. I would have loved for the experience to be a bit longer but i still liked it. https://www.experienceflyover.com/chicago/?gad_source=1&gclid=CjwKCAiArva5BhBiEiwA-oTnXW7uAPFCTQKcn1HQP3UOPSkCzDd7-V0q_e4-bTXVM0HEN8cxXzXDdhoCu8QQAvD_BwE
It's not the Maldives but there are some nice beaches along the lakefront as well. That's one of the things I love about living here, being able to live in a major city and yet I can cycle with my daughter to the nearby beach in 20 mins.
One thing that surprises visitors to Chicago is how large Lake Michigan is, it looks like the sea but it's really a massive freshwater lake that borders 4 states and Chicago has done a great job preserving the lakefront for public use.
The Chicago Riverwalk is also beautiful and a good way to spend an evening walking along the river, lots of bars and restaurants and activities. I love sitting along the river with a drink watching the boats, yachts and kayaks etc go by: https://m.youtube.com/watch?v=VaE4W0rpYHU
This guy also has some videos about Chicago including tours of different neighborhoods and restaurants etc: https://m.youtube.com/@toursbyfootchicago/videos
The main sports league still in season in June is baseball so if interested I would recommend a game at Wrigley Field one of the oldest baseball park in the US to watch the Chicago Cubs play (there are 2 baseball teams Chicago Cubs and Chicago White Sox). It's a fun environment, I love how they pull out their W flags when the team wins and sing their victory song. Also Wrigley Field has a special place in my heart because that's where I had my oath ceremony to naturalize as a US citizen.
There's also the free Lincoln Park Zoo which is located within Lincoln Park Chicago's equivalent of Central Park, and there are lots of restaurants and things to do in the Lincoln Park neighborhood as well.
You also don't need a car, you can easily get around with the bus, train, Uber, walking or cycling unless you're planning a trip outside Chicago to one of the smaller towns or something.
Fun fact: Chicago has the largest number of lifting bridges in the US and it's fun to see them lift up to allow the boats to buy in spring and fall. Unfortunately they don't lift up that often in summer so you probably wouldn't see it but they lift up on spring to allow boats return to the lake after winter and in fall for boats to leave the lake for winter.
Anyway good luck with your decision, the planning and the trip. Let us know if you have any other questions.