bite off more than one can chew

/B AY1 T AO0 F M AO0 R DH AE0 N W AH0 N K AE0 N CH UW0/
verb
  1. 1

    To try to do too much; to take on or attempt more than one is capable of doing.

    โ€œI think I bit off more than I could chew when I agreed to paint this house by myself.โ€

Source: https://en.wiktionary.org/wiki/bite%20off%20more%20than%20one%20can%20chew