If you have time for a little road trip check out Middleton Place, a beautiful plantation with lots of history and exhibits as well as a nice restaurant. We enjoyed Vikery's restaurant in Shem Creek where you can eat overlooking the shrimp boats. If you go for sweetgrass baskets you can get better deals on the Sweetgrass Highway which has stands set up on the sides. Patriot Point was interesting and our son enjoyed showing us the diesel sub - hard to imagine living on that!
My husband and I enjoyed Middleton Plantation when we went out for our son's Prototype graduation. He wanted to go play games with his friends still at RTC, so we took a tour by ourselves. I believe Magnolia might have a larger garden, but Middleton Plantaion was very interesting, lots of history, They were having an Easter Egg hunt when we were there. I will say though their little restaraunt is very price and they were doing an Easter buffet so it was even more expensive and we were headed to dinner becuase our son was taking us to a very fancy eating establishment that his roommate's father told him to take us. So fancy, I don't recall it's name.
They do have alligators at Middleton Place so if you are squimish about that then go elsewhere.
If you want to see historic Charleston and don't want to spend much, you can do like we did and park on the street on Murray Blvd near The Battery and do your own walking tour. White Point Gardens has several statues and historic markers; although some may have been removed by now. East Battery turns into East Bay street which is where Rainbow Row is. We walked to the wharf to take pictures of Patriots Point and see the pier where my son proposed to his girlfriend. There are also several places along the way to take pictures of Ft. Sumter. Charleston has plenty easily spotted plaques and markers for history buffs and water features with benches for the weary. Pre-pandemic there were several cute shops on Market Street. We didn't use the DASH, but it is free if your feet wear out. Most hotels have free visitors guides and maps of Peninsula Charleston with landmarks listed. Be sure to check the weather before you head out.