High industry fixed costs and Porter's 5 forces

New entrants: high fixed costs imply considerable amounts of building, plant and machinery (eg depreciation and rent). If so, the capital investment needed would tend to be a barrier to entrance.

Rivalry: high fixed costs imply that, to cover these, the company will need to operate at high capacity and this is likely to intensify competition.

Customers and suppliers: if they know you have to cover your high fixed costs, this can give them a lever.

Substitutes: I don’t think this is consistently affected by high fixed costs (the substitute might or might not also have high fixed costs).