Direct debit

I’ve done a quote for electricity direct debit it says 61 pound a month can you use as much electricity as need and it still stays at 61 pound a month

In theory yes but if you continually use more than the dd then Bulb would request you increase the DD.
Your quote if determined by you submitting your years usage then the DD would be 1 year usage divided by 12.
Generally you use more than you pay during winter and pay more than you use during warmer months so it balances out over the year.

I've done a quote for electricity direct debit it says 61 pound a month can you use as much electricity as need and it still stays at 61 pound a month

No. It’s not an all-you-can-eat plan. The quote is based on an estimate of your typical usage. If you use more you will pay more, although as @scudo says this may not be immediately reflected in your direct debit payment.