There are probably a lot of technique books available and information on forums, etc. I think the classic technique book for trumpet would be
Arban's. I'm not a trumpet player now, but I played it for about a decade as a third or fourth instrument. Back when I was still playing trumpet (going on 20 years ago), one of the top professional players I knew loaned me his copy of "Super Power Embouchure". I still remember the title somehow. This book helped me a fair bit because it's about developing muscle strength in the face, away from the horn, using isometric exercises, so you can work the face while driving or grocery shopping or whatever. I looked up the book and it is available online
here. There's a complete set of books for embouchure, breath control, and tonguing by the same author, available
here. I'm only familiar with the embouchure book and I'm not guaranteeing these books are any good, but from what I remember, the method was pretty well conceived, and I was able to increase my range up to a usable high F before I quit trumpet for good. Good luck! Trumpet is a hard instrument IMHO. YMMV.