For A2C, the values you're looking for are located in the docs here:
https://stable-baselines3.readthedocs.io/en/master/modules/a2c.html#stable_baselines3.a2c.A2C
class stable_baselines3.a2c.A2C(policy, env, learning_rate=0.0007, n_steps=5, gamma=0.99, gae_lambda=1.0, ent_coef=0.0, vf_coef=0.5, max_grad_norm=0.5, rms_prop_eps=1e-05, use_rms_prop=True, use_sde=False, sde_sample_freq=-1, normalize_advantage=False, tensorboard_log=None, policy_kwargs=None, verbose=0, seed=None, device='auto', _init_setup_model=True)
For PPO, the values are located here:
https://stable-baselines3.readthedocs.io/en/master/modules/ppo.html#stable_baselines3.ppo.PPO
class stable_baselines3.ppo.PPO(policy, env, learning_rate=0.0003, n_steps=2048, batch_size=64, n_epochs=10, gamma=0.99, gae_lambda=0.95, clip_range=0.2, clip_range_vf=None, normalize_advantage=True, ent_coef=0.0, vf_coef=0.5, max_grad_norm=0.5, use_sde=False, sde_sample_freq=-1, target_kl=None, tensorboard_log=None, policy_kwargs=None, verbose=0, seed=None, device='auto', _init_setup_model=True)
The docs contain brief explanations of each of the parameters, but if something is unclear, feel free to ask.
If these weren't the parameters you were looking for, please let me know.