If you can’t/don’t want to practice solely aerials/pole all the time, it’s a good idea to supplement your training with other forms of exercise. You should do what you enjoy, but if you’re looking for ideas, there’s a couple that are particularly popular among aerial enthusiasts for different reasons.
Depending on the chosen form of yoga, it can help a lot with flexibility, core strength, body awareness and general mobility. The more active styles are for example vinyasa, ashtanga or rocket. If you’re just interested in flexibility, try yin.
Yoga is popular enough that it should be relatively easy to find classes, or you can just practice at home, perhaps with the help of a Youtube video. No special equipment besides a mat necessary.
Of course there’s also aerial yoga, which is a blend of yoga and circus. It is performed on a hammock (sling). It’s closer to hatha yoga as it has little flow, and is often less meditative than regular yoga. Although it depends on how it’s taught, it generally requires less strength than silks or slings. For example, while you will probably do inverts, they’re not pure strength based like pike. Instead it’s more about leaning into the hammock and getting used to going upside down.
Climbing will build full body strength. It helps especially with upper body, forearm and grip, all of which are useful in aerials and can be tricky to find elsewhere. It can also help you get more comfortable with heights.
For this you’ll need to find a more specialized gym. You’ll also need to learn how to belay (unless you’re just bouldering, which you can do on your own) and find appropriate footwear. So it take a bit more effort, but can be very fun too.
Lifting heavy weights is probably one of the fastest ways to build strength, if that’s your key focus. It can also train grip and lets you focus on your problem areas.
Most gyms will have some weights. It can be worth spending a bit more time searching to make sure they have all equipment you need, preferably in multiples, so you don’t have to wait too long. You could also buy weights for home if you’re serious about it.