pip3 install --user --break-system-packages pymupdf

import fitz

doc = fitz.open("input.pdf")
for page in doc:
    instances = page.search_for("text to find")
    for inst in instances:
        highlight = page.add_highlight_annot(inst)
        highlight.set_colors(stroke=(1, 1, 0))  # Yellow
        highlight.update()
doc.save("output.pdf")

import fitz

merged = fitz.open()
for pdf_path in ["doc1.pdf", "doc2.pdf"]:
    merged.insert_pdf(fitz.open(pdf_path))
merged.save("merged.pdf")

import fitz

doc = fitz.open("input.pdf")
new_doc = fitz.open()
new_doc.insert_pdf(doc, from_page=5, to_page=10)  # Pages 6-11 (0-indexed)
new_doc.save("extract.pdf")

import fitz

doc = fitz.open("input.pdf")
for page in doc:
    text = page.get_text()
    print(text)

import fitz

doc = fitz.open("input.pdf")
page = doc[0]
rect = fitz.Rect(100, 100, 200, 120)
page.insert_textbox(rect, "Added text", fontsize=12)
doc.save("output.pdf")