How to get big with No weights?
Check out what's available locally as far as exercise equipment in parks. Pullup bars, parallel bars. Stuff like that. Body weight exercise can be great especially with equipment that allows you to use max weight.
You can invest in a pullup bar for home. Dips between two chairs with heels on floor or propped up on something higher for more weight. Pushups are underrated and great. You can progress to using a backpack with heavier and heavier loads on body weight exercises too, or a weight vest if you want to invest a little.
For legs, body weight squats and especially pistols which are basically one-legged squats, so more weight (i do pistols on a stool for easier balance as i get better) and lunges and other exercises are great for leg muscles. You can hold jugs of water and do lunge walk...things like that. Try different things to maximize results while staying safe/ comfortable but not bored.