Suez did not impose a Panama-style cruiser constraint

Did the Suez Canal affect Royal Navy protected-cruiser design in beam or draft?

No; Suez was wide and deep enough that it did not create a Panama-style dimensional restriction.

Passage through Suez did not impose a meaningful restriction on Royal Navy protected-cruiser dimensions. The canal was considerably wider and deeper than the Panama Canal constraints familiar from later warship design. Suez remained strategically vital as a deployment route. These cruisers needed no special narrow-beam or shallow-draft compromise to use it.