Boston Modern Orchestra Project will present its first public performance in more than 18 months on February 18 at Boston’s Symphony Hall. The concert, “Pulling Out All the Stops,” launches the ensemble’s 25th-anniversary year and will feature organ soloist Paul Jacobs in concertos by Stephen Paulus and Joseph Jongen alongside works by J.S. Bach (Fantasia and Fugue in C minor, BWV 537, arranged by Edward Elgar) and Olivier Messiaen (L’ascension). The orchestra is offering free admission to the concert, which is being performed in memory of Ellis L. Phillips III, BMOP’s longtime board chair. All visitors to Symphony Hall must present either proof of vaccination or a negative COVID-19 test to enter, and CDC-approved masks are required while in the hall. On April 8 in Boston’s Jordan Hall, BMOP will perform music by Ellen Taafe Zwilich and the world premiere of New England Conservatory Composition Competition winner Lavell Blackwell’s Effleurage. Gil Rose is artistic director of Boston Modern Orchestra Project.