Sometimes the lease will specifically reference the Residential Tenancies Act and sometimes the lease won’t mention the law at all. The law will still apply regardless of whether the lease mentions it.
Tenants cannot waive any of the rights that they have under the Residential Tenancies Act. For example, if the lease says that the landlord can give a monthly periodic tenant a one week notice to move out if they don’t pay rent, then that part of the tenancy agreement is not enforceable. This is because the law says that a tenant in that situation should get a 14 day notice.