A Study to Evaluate TAR-210 Versus Single Agent Intravesical Cancer Treatment in Participants With Bladder Cancer

Inclusion Criteria: * Main study only: Have a histologically confirmed diagnosis (within 90 days of randomization) of IR-NMIBC with at least one of the following criteria fulfilled: a. Ta low grade (LG)/ Grade 1 (G1): primary or recurrent, b. Ta LG/G2: primary or recurrent and c. Greater than or equal to (\>=) 1 of the following risk factors: i. Multiple Ta LG tumors, ii. Solitary LG tumor \>= 3 cm, iii. Early recurrence (less than \[\<\] 1 year), iv. Frequent recurrence (greater than \[\>\] 1 per year), v. Recurrence after prior adjuvant intravesical treatment (single perioperative dose of chemotherapy does not fulfill this risk factor) * Substudy only: Have a histologically confirmed new diagnosis (within 90 days of randomization) of IR-NMIBC for whom MMC is deemed the therapy of choice according to local standard of care with at least 1 of the following criteria fulfilled: a. Ta LG/G1, b. Ta LG/G2, and \>=1 of the following risk factors: i) Multiple Ta LG tumors, ii) Solitary LG tumor \>=3 cm * Have a susceptible fibroblast growth factor receptor (FGFR) mutation or fusion either by urine testing or tumor tissue testing (from TURBT tissue), as determined by central or local testing * Participants must be willing to undergo all study procedures (e.g., multiple cystoscopies from Screening through the end of study and TURBT for assessment of recurrence/progression) and receive the assigned treatment, including intravesical chemotherapy if randomized into that arm. * Visible p…