from diffusers import AutoPipelineForText2Image
import torch

pipeline = AutoPipelineForText2Image.from_pretrained('lodestones/Chroma1-Base', torch_dtype=torch.bfloat16).to('cuda')
pipeline.load_lora_weights('YuLexuan30/chromaloonerv3-lora', weight_name='chromaloonerv3_000002250.safetensors')
image = pipeline('a beautiful landscape').images[0]
image.save("my_image.png")

For more details, including weighting, merging and fusing LoRAs, check the documentation on loading LoRAs in diffusers