Nemtabrutinib and Venetoclax for the Treatment of Patients With Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma

Inclusion Criteria: * Confirmed diagnosis of CLL/SLL meeting criteria established in the 2018 International Workshop on Chronic Lymphocytic Leukemia (iwCLL) guidelines * Is an individual of any sex/gender, who is at least 18 years of age on the day of signing informed consent * Participants must have treatment-naïve CLL/SLL. Palliative loco-regional radiotherapy, rituximab for autoimmune conditions, or corticosteroids for symptom control will not be considered prior therapy * Participants must meet criteria for treatment as defined by 2018 iwCLL guidelines which includes at least one of the following criteria: * Massive (\>= 6 cm below the costal margin), progressive or symptomatic splenomegaly * Massive nodes (\>= 10 cm) or progressive or symptomatic lymphadenopathy * Progressive lymphocytosis with a lymphocyte doubling time \< 6 months or an increase of \>= 50% over a 2 month period * Autoimmune anemia and/or thrombocytopenia that is poorly responsive to standard therapy * Symptomatic or functional extranodal involvement (e.g. skin, kidney, lung, spine) * Constitutional symptoms, which include any of the following: * Unintentional weight loss of 10% or more within 6 months * Significant fatigue * Fevers \> 100.5 degrees Fahrenheit (F) for 2 weeks or more without evidence of infection * Night sweats \>= 1 month without evidence of infection * Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2. Evaluation of ECOG is to be performed within 7 days prior to the first dose of study intervention * Adequate bone marrow independent of growth factor support or infusion support at screening unless evidence shows that the cytopenia(s) is due to marrow involvement by CLL/SLL and/or disease-related immune thrombocytopenia, or anemia. If cytopenias are due to disease in the bone marrow any degree of cytopenias are allowed. Patients with active uncontrolled autoimmune cytopenias are excluded * Absolute neutrophil count (ANC) \>= 1000/mm\^3 * Platelets \>= 50,000/mm\^3 * Hemoglobin \>= 8 g/dL * Willing and able to participate in all required evaluations and procedures in this study protocol * Ability to understand the purpose and risks of the study and provide signed and dated informed consent and authorization to use protected health information * Participants assigned male sex at birth: If capable of producing sperm, the participant agrees to the following during the intervention period and for at least the time needed to eliminate each study intervention after the last dose of study intervention. The length of time required to continue contraception for each study intervention is: * Nemtabrutinib: 12 days * Abstains from penile-vaginal intercourse as their preferred and usual lifestyle (abstinent on a long-term and persistent basis) and agrees to remain abstinent OR * Uses contraception as detailed below unless confirmed to be azoospermic (vasectomized or secondary to medical cause, documented from the site personnel's review of the participant's medical records, medical examination, or medical history interview) as detailed below: * Uses a penile/external condom plus nonparticipant of childbearing potential who is not currently pregnant and should also be advised of the benefit for that partner to use an additional method of contraception, as a condom may break or leak. * Note: Participants capable of producing ejaculate whose partner is pregnant or breastfeeding must agree to use penile/external condom during each episode of sexual activity in which the partner is at risk of drug exposure via ejaculate. * Contraceptive use by participants capable of producing sperm should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies. If the contraception requirements in the local label for any of the study interventions are more stringent than the requirements above, the local label requirements are to be followed * Participants assigned female sex at birth: A participant assigned female sex at birth is eligible to participate if not pregnant or breastfeeding, and at least one of the following conditions applies: * Is not a person of childbearing potential (POCBP) OR * Is a POCBP and: * Uses a contraceptive method that is highly effective (with a failure rate of \< 1% per year), with low user dependency, or is abstinent from penile-vaginal intercourse as their preferred and usual lifestyle (abstinent on a long-term and persistent basis), during the intervention period and for at least the time needed to eliminate each study intervention after the last dose of study intervention. The length of time required to continue contraception for each study intervention is: * Nemtabrutinib: 1 month * The investigator should evaluate the potential for contraceptive method failure (i.e., noncompliance, recently initiated) in relationship to the first dose of study intervention. Contraceptive use by POCBPs should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies. If the contraception requirements in the local label for any of the study interventions are more stringent than the requirements above, the local label requirements are to be followed. * Has a negative highly sensitive pregnancy test (urine or serum) as required by local regulations within 24 hours (for urine test) or 72 hours (for serum test) before the first dose of study intervention. If a urine test cannot be confirmed as negative (e.g., an ambiguous result), a serum pregnancy test is required. In such cases, the participant must be excluded from participation if the serum pregnancy result is positive. * Abstains from breastfeeding during the study intervention period and for at least 30 days after study intervention with nemtabrutinib. * Medical history, menstrual history, and recent sexual activity has been reviewed by the inves