I still don’t think I understand you.
But if you just want to have Linear and ReLU in sequence and callable in one, than this works:
import torch.nn as nn

Linear_ReLU_fusion = nn.Sequential(nn.Linear(in_features, out_features),
                                   nn.ReLU()
                                   )

you could then just call it in one go
out = Linear_ReLU_fusion(x)

e.g.
import torch.nn as nn

Linear_ReLU_fusion = nn.Sequential(nn.Linear(3072, 10),
                                   nn.ReLU()
                                   )
x = torch.rand(1, 3, 32, 32)
x = x.view(-1, 3072)
out = Linear_ReLU_fusion(x)

works fine!