No, once money is paid into a SIPP you cannot normally access the money until age 55. The minimum age will rise to 57 in 2028 and then in line with increases in the state pension age, remaining 10 years below (e.g. if the state pension age rises to 68, the minimum retirement age will rise to 58).
If you are unsure if a SIPP is right for you, you should speak to a financial adviser.
Find out more about accessing your pension.